The Administrator may promulgate criteria similar to that referenced in subpart B of this part for monitoring a pollutant for which an NAAQS does not exist. Such an action would be taken whenever the Administrator determines that a nationwide monitoring program is necessary to monitor such a pollutant. [71 FR 61303, Oct. 17, 2006]
Sec. Appendix A to Part 58--Quality Assurance Requirements for SLAMS,
SPMs and PSD Air Monitoring 1. General Information2. Quality System Requirements3. Measurement Quality Check Requirements4. Calculations for Data Quality Assessments5. Reporting Requirements6. References
1. General Information.
(a) Each monitoring organization is required to implement a quality system that provides sufficient information to assess the quality of the monitoring data. The quality system must, at a minimum, include the specific requirements described in this appendix of this subpart. Failure to conduct or pass a required check or procedure, or a series of required checks or procedures, does not by itself invalidate data for regulatory decision making. Rather, monitoring agencies and EPA shall use the checks and procedures required in this appendix in combination with other data quality information, reports, and similar documents showing overall compliance with part 58. Accordingly, EPA and monitoring agencies shall use a ``weight of evidence'' approach when determining the suitability of data for regulatory decisions. The EPA reserves the authority to use or not use monitoring data submitted by a monitoring organization when making regulatory decisions based on the EPA's assessment of the quality of the data. Generally, consensus built validation templates or validation criteria already approved in Quality Assurance Project Plans (QAPPs) should be used as the basis for the weight of evidence approach.
(b) This appendix specifies the minimum quality system requirements applicable to SLAMS air monitoring data and PSD data for the pollutants SO2, NO2, O3, CO, Pb, PM 2.5, PM 10 and PM 10-2.5 submitted to EPA. This appendix also applies to all SPM stations using FRM, FEM, or ARM methods which also meet the requirements of appendix E of this part, unless alternatives to this appendix for SPMs have been approved in accordance with Sec. 58.11(a)(2). Monitoring organizations are encouraged to develop and maintain quality systems more extensive than the required minimums. The permit-granting authority for PSD may require more frequent or more stringent requirements. Monitoring organizations may, based on their quality objectives, develop and maintain quality systems beyond the required minimum. Additional guidance for the requirements reflected in this appendix can be found in the ``Quality Assurance Handbook for Air Pollution Measurement Systems'', Volume II (see reference 10 of this appendix) and at a national level in references 1, 2, and 3 of this appendix.
1.1 Similarities and Differences Between SLAMS and PSD Monitoring. In most cases, the quality assurance requirements for SLAMS, SPMs if applicable, and PSD are the same. Affected SPMs are subject to all the SLAMS requirements, even where not specifically stated in each section. Table A-1 of this appendix summarizes the major similarities and differences of the requirements for SLAMS and PSD. Both programs require:
(a) The development, documentation, and implementation of an approved quality system;
(b) The assessment of data quality;
(c) The use of reference, equivalent, or approved methods. The requirements of this appendix do not apply to a SPM that does not use a FRM, FEM, or ARM;
(d) The use of calibration standards traceable to NIST or other primary standard;
(e) Performance evaluations and systems.
1.1.1 The monitoring and quality assurance responsibilities for SLAMS are with the State or local agency, hereafter called the monitoring organization, whereas for PSD they are with the owner/operator seeking the permit. The monitoring duration for SLAMS is indefinite, whereas for PSD the duration is usually 12 months. Whereas the reporting period for precision and accuracy data is on an annual or calendar quarter basis for SLAMS, it is on a continuing sampler quarter basis for PSD, since the monitoring may not commence at the beginning of a calendar quarter.
1.1.2 The annual performance evaluations (described in section 3.2.2 of this appendix) for PSD must be conducted by personnel different from those who perform routine span checks and calibrations, whereas for SLAMS, it is the preferred but not the required condition. For PSD, the evaluation rate is 100 percent of the sites per reporting quarter whereas for SLAMS it is 25 percent of the sites or instruments quarterly. Monitoring for sulfur dioxide (SO2) and nitrogen dioxide (NO2) for PSD must be done with automated analyzers--the manual bubbler methods are not permitted.
1.1.3 The requirements for precision assessment for the automated methods are the same for both SLAMS and PSD. However, for manual methods, only one collocated site is required for PSD.
1.1.4 The precision, accuracy and bias data for PSD are reported separately for each sampler (site), whereas for SLAMS, the report may be by sampler (site), by primary quality assurance organization, or nationally, depending on the pollutant. SLAMS data are required to be reported to the AQS, PSD data are required to be reported to the permit-granting authority. Requirements in this appendix, with the exception of the differences discussed in this section, and in Table A-1 of this appendix will be expected to be followed by both SLAMS and PSD networks unless directly specified in a particular section.
1.2 Measurement Uncertainty. Measurement uncertainty is a term used to describe deviations from a true concentration or estimate that are related to the measurement process and not to spatial or temporal population attributes of the air being measured. Monitoring organizations must develop quality assurance project plans (QAPP) which describe how the organization intends to control measurement uncertainty to an appropriate level in order to achieve the objectives for which the data are collected. The process by which one determines the quality of data needed to meet the monitoring objective is sometimes referred to the Data Quality Objectives Process. Data quality indicators associated with measurement uncertainty include:
(a) Precision. A measurement of mutual agreement among individual measurements of the same property usually under prescribed similar conditions, expressed generally in terms of the standard deviation.
(b) Bias. The systematic or persistent distortion of a measurement process which causes errors in one direction.
(c) Accuracy. The degree of agreement between an observed value and an accepted reference value. Accuracy includes a combination of random error (imprecision) and systematic error (bias) components which are due to sampling and analytical operations.
(d) Completeness. A measure of the amount of valid data obtained from a measurement system compared to the amount that was expected to be obtained under correct, normal conditions.
(e) Detectability. The low critical range value of a characteristic that a method specific procedure can reliably discern.
1.3 Measurement Quality Checks. The SLAMS measurement quality checks described in sections 3.2 and 3.3 of this appendix shall be reported to AQS and are included in the data required for certification. The PSD network is required to implement the measurement quality checks and submit this information quarterly along with assessment information to the permit-granting authority.
1.4 Assessments and Reports. Periodic assessments and documentation of data quality are required to be reported to EPA or to the permit granting authority (PSD). To provide national uniformity in this assessment and reporting of data quality for all networks, specific assessment and reporting procedures are prescribed in detail in sections 3, 4, and 5 of this appendix. On the other hand, the selection and extent of the quality assurance and quality control activities used by a monitoring organization depend on a number of local factors such as field and laboratory conditions, the objectives for monitoring, the level of data quality needed, the expertise of assigned personnel, the cost of control procedures, pollutant concentration levels, etc. Therefore, quality system requirements in section 2 of this appendix are specified in general terms to allow each monitoring organization to develop a quality system that is most efficient and effective for its own circumstances while achieving the data quality objectives required for the SLAMS sites.
2. Quality System Requirements
A quality system is the means by which an organization manages the quality of the monitoring information it produces in a systematic, organized manner. It provides a framework for planning, implementing, assessing and reporting work performed by an organization and for carrying out required quality assurance and quality control activities.
2.1 Quality Management Plans and Quality Assurance Project Plans. All monitoring organizations must develop a quality system that is described and approved in quality management plans (QMP) and quality assurance project plans (QAPP) to ensure that the monitoring results:
(a) Meet a well-defined need, use, or purpose;
(b) Provide data of adequate quality for the intended monitoring objectives;
(c) Satisfy stakeholder expectations;
(d) Comply with applicable standards specifications;
(e) Comply with statutory (and other) requirements of society; and
(f) Reflect consideration of cost and economics.
2.1.1 The QMP describes the quality system in terms of the organizational structure, functional responsibilities of management and staff, lines of authority, and required interfaces for those planning, implementing, assessing and reporting activities involving environmental data operations (EDO). The QMP must be suitably documented in accordance with EPA requirements (reference 2 of this appendix), and approved by the appropriate Regional Administrator, or his or her representative. The quality system will be reviewed during the systems audits described in section 2.5 of this appendix. Organizations that implement long-term monitoring programs with EPA funds should have a separate QMP document. Smaller organizations or organizations that do infrequent work with EPA funds may combine the QMP with the QAPP based on negotiations with the funding agency. Additional guidance on this process can be found in reference 10 of this appendix. Approval of the recipient's QMP by the appropriate Regional Administrator or his or her representative, may allow delegation of the authority to review and approve the QAPP to the recipient, based on adequacy of quality assurance procedures described and documented in the QMP. The QAPP will be reviewed by EPA during systems audits or circumstances related to data quality.
2.1.2 The QAPP is a formal document describing, in sufficient detail, the quality system that must be implemented to ensure that the results of work performed will satisfy the stated objectives. The quality assurance policy of the EPA requires every environmental data operation (EDO) to have a written and approved QAPP prior to the start of the EDO. It is the responsibility of the monitoring organization to adhere to this policy. The QAPP must be suitably documented in accordance with EPA requirements (reference 3 of this appendix).
2.1.3 The monitoring organization's quality system must have adequate resources both in personnel and funding to plan, implement, assess and report on the achievement of the requirements of this appendix and its approved QAPP.
2.2 Independence of Quality Assurance. The monitoring organization must provide for a quality assurance management function- that aspect of the overall management system of the organization that determines and implements the quality policy defined in a monitoring organization's QMP. Quality management includes strategic planning, allocation of resources and other systematic planning activities (e.g., planning, implementation, assessing and reporting) pertaining to the quality system. The quality assurance management function must have sufficient technical expertise and management authority to conduct independent oversight and assure the implementation of the organization's quality system relative to the ambient air quality monitoring program and should be organizationally independent of environmental data generation activities.
2.3. Data Quality Performance Requirements.
2.3.1 Data Quality Objectives. Data quality objectives (DQO) or the results of other systematic planning processes are statements that define the appropriate type of data to collect and specify the tolerable levels of potential decision errors that will be used as a basis for establishing the quality and quantity of data needed to support the objectives of the SLAMS stations. DQO will be developed by EPA to support the primary SLAMS objectives for each criteria pollutant. As they are developed they will be added to the regulation. DQO or the results of other systematic planning processes for PSD or other monitoring will be the responsibility of the monitoring organizations. The quality of the conclusions made from data interpretation can be affected by population uncertainty (spatial or temporal uncertainty) and measurement uncertainty (uncertainty associated with collecting, analyzing, reducing and reporting concentration data). This appendix focuses on assessing and controlling measurement uncertainty.
2.3.1.1 Measurement Uncertainty for Automated and Manual PM 2.5 Methods. The goal for acceptable measurement uncertainty is defined as 10 percent coefficient of variation (CV) for total precision and plus or minus 10 percent for total bias.
2.3.1.2 Measurement Uncertainty for Automated Ozone Methods. The goal for acceptable measurement uncertainty is defined for precision as an upper 90 percent confidence limit for the coefficient variation (CV) of 7 percent and for bias as an upper 95 percent confidence limit for the absolute bias of 7 percent.
2.3.1.3 Measurement Uncertainty for PM 10-2.5 Methods. The goal for acceptable measurement uncertainty is defined for precision as an upper 90 percent confidence limit for the coefficient variation (CV) of 15 percent and for bias as an upper 95 percent confidence limit for the absolute bias of 15 percent.
2.3.1.4 Measurement Uncertainty for Pb Methods. The goal for acceptable measurement uncertainty is defined for precision as an upper 90 percent confidence limit for the coefficient variation (CV) of 20 percent and for bias as an upper 95 percent confidence limit for the absolute bias of 15 percent.
2.3.1.5 Measurement Uncertainty for NO2. The goal for acceptable measurement uncertainty is defined for precision as an upper 90 percent confidence limit for the coefficient of variation (CV) of 15 percent and for bias as an upper 95 percent confidence limit for the absolute bias of 15 percent.
2.3.1.6 Measurement Uncertainty for SO2. The goal for acceptable measurement uncertainty for precision is defined as an upper 90 percent confidence limit for the coefficient of variation (CV) of 10 percent and for bias as an upper 95 percent confidence limit for the absolute bias of 10 percent.
2.4 National Performance Evaluation Programs. Monitoring plans or the QAPP shall provide for the implementation of a program of independent and adequate audits of all monitors providing data for SLAMS and PSD including the provision of adequate resources for such audit programs. A monitoring plan (or QAPP) which provides for monitoring organization participation in EPA's National Performance Audit Program (NPAP) and the PM Performance Evaluation Program (PEP) program and which indicates the consent of the monitoring organization for EPA to apply an appropriate portion of the grant funds, which EPA would otherwise award to the monitoring organization for monitoring activities, will be deemed by EPA to meet this requirement. For clarification and to participate, monitoring organizations should contact either the appropriate EPA Regional Quality Assurance (QA) Coordinator at the appropriate EPA Regional Office location, or the NPAP Coordinator at the Air Quality Assessment Division, Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency in Research Triangle Park, North Carolina.
2.5 Technical Systems Audit Program. Technical systems audits of each ambient air monitoring organization shall be conducted at least every 3 years by the appropriate EPA Regional Office and reported to the AQS. Systems audit programs are described in reference 10 of this appendix. For further instructions, monitoring organizations should contact the appropriate EPA Regional QA Coordinator.
2.6 Gaseous and Flow Rate Audit Standards.
2.6.1 Gaseous pollutant concentration standards (permeation devices or cylinders of compressed gas) used to obtain test concentrations for carbon monoxide (CO), sulfur dioxide (SO2), nitrogen oxide (NO), and nitrogen dioxide (NO2) must be traceable to either a National Institute of Standards and Technology (NIST) Traceable Reference Material (NTRM) or a NIST-certified Gas Manufacturer's Internal Standard (GMIS), certified in accordance with one of the procedures given in reference 4 of this appendix. Vendors advertising certification with the procedures provided in reference 4 of this appendix and distributing gasses as ``EPA Protocol Gas'' must participate in the EPA Protocol Gas Verification Program or not use ``EPA'' in any form of advertising.
2.6.2 Test concentrations for ozone (O3) must be obtained in accordance with the ultra violet photometric calibration procedure specified in appendix D to part 50 of this chapter, or by means of a certified O3 transfer standard. Consult references 7 and 8 of this appendix for guidance on primary and transfer standards for O3.
2.6.3 Flow rate measurements must be made by a flow measuring instrument that is traceable to an authoritative volume or other applicable standard. Guidance for certifying some types of flowmeters is provided in reference 10 of this appendix.
2.7 Primary Requirements and Guidance. Requirements and guidance documents for developing the quality system are contained in references 1 through 10 of this appendix, which also contain many suggested procedures, checks, and control specifications. Reference 10 of this appendix describes specific guidance for the development of a quality system for SLAMS. Many specific quality control checks and specifications for methods are included in the respective reference methods described in part 50 of this chapter or in the respective equivalent method descriptions available from EPA (reference 6 of this appendix). Similarly, quality control procedures related to specifically designated reference and equivalent method analyzers are contained in the respective operation or instruction manuals associated with those analyzers.
3. Measurement Quality Check Requirements
This section provides the requirements for primary quality assurance organizations (PQAOs) to perform the measurement quality checks that can be used to assess data quality. With the exception of the flow rate verifications (sections 3.2.3 and 3.3.2 of this appendix), data from these checks are required to be submitted to the AQS within the same time frame as routine ambient concentration data. Section 3.2 of this appendix describes checks of automated or continuous instruments while section 3.3 describe checks associated with manual sampling instruments. Other quality control samples are identified in the various references described earlier and can be used to control certain aspects of the measurement system.
3.1 Primary Quality Assurance Organization. A primary quality assurance organization is defined as a monitoring organization or a coordinated aggregation of such organizations that is responsible for a set of stations that monitors the same pollutant and for which data quality assessments can logically be pooled. Each criteria pollutant sampler/monitor at a monitoring station in the SLAMS network must be associated with one, and only one, primary quality assurance organization.
3.1.1 Each primary quality assurance organization shall be defined such that measurement uncertainty among all stations in the organization can be expected to be reasonably homogeneous, as a result of common factors. Common factors that should be considered by monitoring organizations in defining primary quality assurance organizations include:
(a) Operation by a common team of field operators according to a common set of procedures;
(b) Use of a common QAPP or standard operating procedures;
(c) Common calibration facilities and standards;
(d) Oversight by a common quality assurance organization; and
(e) Support by a common management, laboratory or headquarters.
3.1.2 Primary quality assurance organizations are not necessarily related to the organization reporting data to the AQS. Monitoring organizations having difficulty in defining the primary quality assurance organizations or in assigning specific sites to primary quality assurance organizations should consult with the appropriate EPA Regional Office. All definitions of primary quality assurance organizations shall be subject to final approval by the appropriate EPA Regional Office during scheduled network reviews or systems audits.
3.1.3 Data quality assessment results shall be reported as specified in section 5 of this appendix.
3.2 Measurement Quality Checks of Automated Methods. Table A-2 of this appendix provides a summary of the types and frequency of the measurement quality checks that will be described in this section.
3.2.1 One-Point Quality Control Check for SO2, NO2, O3, and CO. A one-point quality control (QC) check must be performed at least once every 2 weeks on each automated analyzer used to measure SO2, NO2, O3 and CO. The frequency of QC checks may be reduced based upon review, assessment and approval of the EPA Regional Administrator. However, with the advent of automated calibration systems more frequent checking is encouraged. See Reference 10 of this appendix for guidance on the review procedure. The QC check is made by challenging the analyzer with a QC check gas of known concentration (effective concentration for open path analyzers) between 0.01 and 0.10 parts per million (ppm) for SO2, NO2, and O3, and between 1 and 10 ppm for CO analyzers. The ranges allow for appropriate check gas selection for SLAMS sites that may be sampling for different objectives, i.e., trace gas monitoring vs. comparison to National Ambient Air Quality Standards (NAAQS). The QC check gas concentration selected should be related to the routine concentrations normally measured at sites within the monitoring network in order to appropriately reflect the precision and bias at these routine concentration ranges. To check the precision and bias of SLAMS analyzers operating at ranges either above or below the levels identified, use check gases of appropriate concentrations as approved by the appropriate EPA Regional Administrator or their designee. The standards from which check concentrations are obtained must meet the specifications of section 2.6 of this appendix.
3.2.1.1 Except for certain CO analyzers described below, point analyzers must operate in their normal sampling mode during the QC check, and the test atmosphere must pass through all filters, scrubbers, conditioners and other components used during normal ambient sampling and as much of the ambient air inlet system as is practicable. If permitted by the associated operation or instruction manual, a CO point analyzer may be temporarily modified during the QC check to reduce vent or purge flows, or the test atmosphere may enter the analyzer at a point other than the normal sample inlet, provided that the analyzer's response is not likely to be altered by these deviations from the normal operational mode. If a QC check is made in conjunction with a zero or span adjustment, it must be made prior to such zero or span adjustments.
3.2.1.2 Open path analyzers are tested by inserting a test cell containing a QC check gas concentration into the optical measurement beam of the instrument. If possible, the normally used transmitter, receiver, and as appropriate, reflecting devices should be used during the test and the normal monitoring configuration of the instrument should be altered as little as possible to accommodate the test cell for the test. However, if permitted by the associated operation or instruction manual, an alternate local light source or an alternate optical path that does not include the normal atmospheric monitoring path may be used. The actual concentration of the QC check gas in the test cell must be selected to produce an effective concentration in the range specified earlier in this section. Generally, the QC test concentration measurement will be the sum of the atmospheric pollutant concentration and the QC test concentration. If so, the result must be corrected to remove the atmospheric concentration contribution. The corrected concentration is obtained by subtracting the average of the atmospheric concentrations measured by the open path instrument under test immediately before and immediately after the QC test from the QC check gas concentration measurement. If the difference between these before and after measurements is greater than 20 percent of the effective concentration of the test gas, discard the test result and repeat the test. If possible, open path analyzers should be tested during periods when the atmospheric pollutant concentrations are relatively low and steady.
3.2.1.3 Report the audit concentration (effective concentration for open path analyzers) of the QC gas and the corresponding measured concentration (corrected concentration, if applicable, for open path analyzers) indicated by the analyzer. The percent differences between these concentrations are used to assess the precision and bias of the monitoring data as described in sections 4.1.2 (precision) and 4.1.3 (bias) of this appendix.
3.2.2 Annual performance evaluation for SO2, NO2, O3, or CO. Each calendar quarter (during which analyzers are operated), evaluate at least 25 percent of the SLAMS analyzers that monitor for SO2, NO2, O3, or CO such that each analyzer is evaluated at least once per year. If there are fewer than four analyzers for a pollutant within a primary quality assurance organization, it is suggested to randomly evaluate one or more analyzers so that at least one analyzer for that pollutant is evaluated each calendar quarter. The evaluation should be conducted by a trained experienced technician other than the routine site operator.
3.2.2.1 (a) The evaluation is made by challenging the analyzer with audit gas standard of known concentration (effective concentration for open path analyzers) from at least three consecutive audit levels. The audit levels selected should represent or bracket 80 percent of ambient concentrations measured by the analyzer being evaluated: ----------------------------------------------------------------------------------------------------------------
Concentration range, ppm
Audit level ---------------------------------------------------------------------------
O3 SO2 NO2 CO----------------------------------------------------------------------------------------------------------------1................................... 0.02-0.05 0.0003-0.005 0.0002-0.002 0.08-0.102................................... 0.06-0.10 0.006-0.01 0.003-0.005 0.50-1.003................................... 0.11-0.20 0.02-0.10 0.006-0.10 1.50-4.004................................... 0.21-0.30 0.11-0.40 0.11-0.30 5-155................................... 0.31-0.90 0.41-0.90 0.31-0.60 20-50----------------------------------------------------------------------------------------------------------------
(b) An additional 4th level is encouraged for those monitors that have the potential for exceeding the concentration ranges described by the initial three selected.
3.2.2.2 (a) NO2 audit gas for chemiluminescence-type NO2 analyzers must also contain at least 0.08 ppm NO. NO concentrations substantially higher than 0.08 ppm, as may occur when using some gas phase titration (GPT) techniques, may lead to evaluation errors in chemiluminescence analyzers due to inevitable minor NO-NOX channel imbalance. Such errors may be atypical of routine monitoring errors to the extent that such NO concentrations exceed typical ambient NO concentrations at the site. These errors may be minimized by modifying the GPT technique to lower the NO concentrations remaining in the NO2 audit gas to levels closer to typical ambient NO concentrations at the site.
(b) To evaluate SLAMS analyzers operating on ranges higher than 0 to 1.0 ppm for SO2, NO2, and O3 or 0 to 50 ppm for CO, use audit gases of appropriately higher concentration as approved by the appropriate EPA Regional Administrator or the Administrator's designee.
3.2.2.3 The standards from which audit gas test concentrations are obtained must meet the specifications of section 2.6 of this appendix. The gas standards and equipment used for evaluations must not be the same as the standards and equipment used for calibration or calibration span adjustments. For SLAMS sites, the auditor should not be the operator or analyst who conducts the routine monitoring, calibration, and analysis. For PSD sites the auditor must not be the operator or analyst who conducts the routine monitoring, calibration, and analysis.
3.2.2.4 For point analyzers, the evaluation shall be carried out by allowing the analyzer to analyze the audit gas test atmosphere in its normal sampling mode such that the test atmosphere passes through all filters, scrubbers, conditioners, and other sample inlet components used during normal ambient sampling and as much of the ambient air inlet system as is practicable. The exception provided in section 3.2.1 of this appendix for certain CO analyzers does not apply for evaluations.
3.2.2.5 Open path analyzers are evaluated by inserting a test cell containing the various audit gas concentrations into the optical measurement beam of the instrument. If possible, the normally used transmitter, receiver, and, as appropriate, reflecting devices should be used during the evaluation, and the normal monitoring configuration of the instrument should be modified as little as possible to accommodate the test cell for the evaluation. However, if permitted by the associated operation or instruction manual, an alternate local light source or an alternate optical path that does not include the normal atmospheric monitoring path may be used. The actual concentrations of the audit gas in the test cell must be selected to produce effective concentrations in the evaluation level ranges specified in this section of this appendix. Generally, each evaluation concentration measurement result will be the sum of the atmospheric pollutant concentration and the evaluation test concentration. If so, the result must be corrected to remove the atmospheric concentration contribution. The corrected concentration is obtained by subtracting the average of the atmospheric concentrations measured by the open path instrument under test immediately before and immediately after the evaluation test (or preferably before and after each evaluation concentration level) from the evaluation concentration measurement. If the difference between the before and after measurements is greater than 20 percent of the effective concentration of the test gas standard, discard the test result for that concentration level and repeat the test for that level. If possible, open path analyzers should be evaluated during periods when the atmospheric pollutant concentrations are relatively low and steady. Also, if the open path instrument is not installed in a permanent manner, the monitoring path length must be reverified to within plus or minus 3 percent to validate the evaluation, since the monitoring path length is critical to the determination of the effective concentration.
3.2.2.6 Report both the evaluation concentrations (effective concentrations for open path analyzers) of the audit gases and the corresponding measured concentration (corrected concentrations, if applicable, for open path analyzers) indicated or produced by the analyzer being tested. The percent differences between these concentrations are used to assess the quality of the monitoring data as described in section 4.1.4 of this appendix.
3.2.3 Flow Rate Verification for Particulate Matter. A one-point flow rate verification check must be performed at least once every month on each automated analyzer used to measure PM 10, PM 10-2.5 and PM 2.5. The verification is made by checking the operational flow rate of the analyzer. If the verification is made in conjunction with a flow rate adjustment, it must be made prior to such flow rate adjustment. Randomization of the flow rate verification with respect to time of day, day of week, and routine service and adjustments is encouraged where possible. For the standard procedure, use a flow rate transfer standard certified in accordance with section 2.6 of this appendix to check the analyzer's normal flow rate. Care should be used in selecting and using the flow rate measurement device such that it does not alter the normal operating flow rate of the analyzer. Report the flow rate of the transfer standard and the corresponding flow rate measured (indicated) by the analyzer. The percent differences between the audit and measured flow rates are used to assess the bias of the monitoring data as described in section 4.2.2 of this appendix (using flow rates in lieu of concentrations).
3.2.4 Semi-Annual Flow Rate Audit for Particulate Matter. Every 6 months, audit the flow rate of the PM 10, PM 10-2.5 and PM 2.5 particulate analyzers. Where possible, EPA strongly encourages more frequent auditing. The audit should (preferably) be conducted by a trained experienced technician other than the routine site operator. The audit is made by measuring the analyzer's normal operating flow rate using a flow rate transfer standard certified in accordance with section 2.6 of this appendix. The flow rate standard used for auditing must not be the same flow rate standard used to calibrate the analyzer. However, both the calibration standard and the audit standard may be referenced to the same primary flow rate or volume standard. Great care must be used in auditing the flow rate to be certain that the flow measurement device does not alter the normal operating flow rate of the analyzer. Report the audit flow rate of the transfer standard and the corresponding flow rate measured (indicated) by the analyzer. The percent differences between these flow rates are used to validate the one-point flow rate verification checks used to estimate bias as described in section 4.2.3 of this appendix.
3.2.5 Collocated Sampling Procedures for PM 2.5. For each pair of collocated monitors, designate one sampler as the primary monitor whose concentrations will be used to report air quality for the site, and designate the other as the audit monitor.
3.2.5.1 Each EPA designated Federal reference method (FRM) or Federal equivalent method (FEM) within a primary quality assurance organization must:
(a) Have 15 percent of the monitors collocated (values of 0.5 and greater round up); and
(b) Have at least 1 collocated monitor (if the total number of monitors is less than 3). The first collocated monitor must be a designated FRM monitor.
3.2.5.2 In addition, monitors selected for collocation must also meet the following requirements:
(a) A primary monitor designated as an EPA FRM shall be collocated with an audit monitor having the same EPA FRM method designation.
(b) For each primary monitor model designated as an EPA FEM used by the PQAO, 50 percent of the monitors designated for collocation shall be collocated with an audit monitor having the same method designation and 50 percent of the monitors shall be collocated with an FRM audit monitor. If the primary quality assurance organization only has one FEM monitor it shall be collocated with an FRM audit monitor. If there are an odd number of collocated monitors required, the additional monitor shall be an FRM audit monitor. An example of this procedure is found in Table A-3 of this appendix.
3.2.5.3 The collocated monitors should be deployed according to the following protocol:
(a) 80 percent of the collocated audit monitors should be deployed at sites with annual average or daily concentrations estimated to be within [20 percent of the applicable NAAQS and the remainder at what the monitoring organizations designate as high value sites;
(b) If an organization has no sites with annual average or daily concentrations within [20 percent of the annual NAAQS (or 24-hour NAAQS if that is affecting the area), 60 percent of the collocated audit monitors should be deployed at those sites with the annual mean concentrations (or 24-hour NAAQS if that is affecting the area) among the highest 25 percent for all sites in the network.
3.2.5.4 In determining the number of collocated sites required for PM 2.5, monitoring networks for visibility assessments should not be treated independently from networks for particulate matter, as the separate networks may share one or more common samplers. However, for Class I visibility areas, EPA will accept visibility aerosol mass measurement instead of a PM 2.5 measurement if the latter measurement is unavailable. Any PM 2.5 monitoring site which does not have a monitor which is an EPA FRM, FEM or ARM is not required to be included in the number of sites which are used to determine the number of collocated monitors.
3.2.5.5 For each PSD monitoring network, one site must be collocated. A site with the predicted highest 24-hour pollutant concentration must be selected.
3.2.5.6 The two collocated monitors must be within 4 meters of each other and at least 2 meters apart for flow rates greater than 200 liters/min or at least 1 meter apart for samplers having flow rates less than 200 liters/min to preclude airflow interference. A waiver allowing up to 10 meters horizontal distance and up to 3 meters vertical distance (inlet to inlet) between a primary and collocated sampler may be approved by the Regional Administrator for sites at a neighborhood or larger scale of representation. This waiver may be approved during the annual network plan approval process. Calibration, sampling, and analysis must be the same for all the collocated samplers in each agency's network.
3.2.5.7 Sample the collocated audit monitor for SLAMS sites on a 12-day schedule; sample PSD sites on a 6-day schedule or every third day for PSD daily monitors. If a primary quality assurance organization has only one collocated monitor, higher sampling frequencies than the 12-day schedule may be needed in order to produce about 25 valid sample pairs a year. Report the measurements from both primary and collocated audit monitors at each collocated sampling site. The calculations for evaluating precision between the two collocated monitors are described in section 4.3.1 of this appendix.
3.2.6 Collocated Sampling Procedures for PM 10-2.5. For the PM 10-2.5 network, all automated methods must be designated as Federal equivalent methods (FEMs). For each pair of collocated monitors, designate one sampler as the primary monitor whose concentrations will be used to report air quality for the site, and designate the other as the audit monitor.
3.2.6.1 The EPA shall ensure that each EPA designated FEM within the national PM 10-2.5 monitoring network must:
(a) Have 15 percent of the monitors collocated (values of 0.5 and greater round up); and
(b) Have at least 2 collocated monitors (if the total number of monitors is less than 10). The first collocated monitor must be a designated FRM monitor and the second must be a monitor of the same method designation. Both collocated FRM and FEM monitors can be located at the same site.
3.2.6.2 The Regional Administrator for the EPA Regions where the FEMs are implemented will select the sites for collocated monitoring. The site selection process shall consider giving priority to sites at primary quality assurance organizations or States with more than one PM 10-2.5 site, sites considered important from a regional perspective, and sites needed for an appropriate distribution among rural and urban NCore sites. Depending on the speed at which the PM 10-2.5 network is deployed, the first sites implementing FEMs shall be required to perform collocation until there is a larger distribution of FEM monitors implemented in the network.
3.2.6.3 The two collocated monitors must be within 4 meters of each other and at least 2 meters apart for flow rates greater than 200 liters/min or at least 1 meter apart for samplers having flow rates less than 200 liters/ min to preclude airflow interference. A waiver allowing up to 10 meters horizontal distance and up to 3 meters vertical distance (inlet to inlet) between a primary and a collocated sampler may be approved by the Regional Administrator for sites at a neighborhood or larger scale of representation taking into consideration safety, logistics, and space availability. This waiver may be approved during the annual network plan approval process. Calibration, sampling, and analysis must be the same for all the collocated samplers in each agency's network.
3.2.6.4 Sample the collocated audit monitor for SLAMS sites on a 12-day schedule. Report the measurements from both primary and collocated audit monitors at each collocated sampling site. The calculations for evaluating precision between the two collocated monitors are described in section 4.3.1 of this appendix.
3.2.7 PM 2.5 Performance Evaluation Program (PEP) Procedures. The PEP is an independent assessment used to estimate total measurement system bias. These evaluations will be performed under the PM Performance Evaluation Program (PEP) (section 2.4 of this appendix) or a comparable program. Performance evaluations will be performed on the SLAMS monitors annually within each primary quality assurance organization. For primary quality assurance organizations with less than or equal to five monitoring sites, five valid performance evaluation audits must be collected and reported each year. For primary quality assurance organizations with greater than five monitoring sites, eight valid performance evaluation audits must be collected and reported each year. A valid performance evaluation audit means that both the primary monitor and PEP audit concentrations are valid and above 3 g/m\3\. Additionally, each year, every designated FRM or FEM within a primary quality assurance organization must:
(1) Have each method designation evaluated each year; and,
(2) Have all FRM or FEM samplers subject to a PEP audit at least once every six years; which equates to approximately 15 percent of the monitoring sites audited each year.
(b) Additional information concerning the Performance Evaluation Program is contained in reference 10 of this appendix. The calculations for evaluating bias between the primary monitor and the performance evaluation monitor for PM 2.5 are described in section 4.3.2 of this appendix.
3.2.8 PM 10-2.5 Performance Evaluation Program. For the PM 10-2.5 network, all automated methods will be designated as federal equivalent methods (FEMs). One performance evaluation audit, as described in section 3.2.7 must be performed at one PM 10-2.5 site in each primary quality assurance organization each year. The calculations for evaluating bias between the primary monitor(s) and the performance evaluation monitors for PM 10-2.5 are described in section 4.1.3 of this appendix.
3.3 Measurement Quality Checks of Manual Methods. Table A-2 of this appendix provides a summary of the types and frequency of the measurement quality checks that will be described in this section.
3.3.1 Collocated Sampling Procedures for PM 10. For each network of manual PM 10 methods, select 15 percent (or at least one) of the monitoring sites within the primary quality assurance organization for collocated sampling. For purposes of precision assessment, networks for measuring total suspended particulate (TSP) and PM 10 shall be considered separately from one another. However, PM 10 samplers used in the PM 10-2.5 network, may be counted along with the PM 10 samplers in the PM 10 network as long as the PM 10 samplers in both networks are the same method designation. PM 10 and TSP sites having annual mean particulate matter concentrations among the highest 25 percent of the annual mean concentrations for all the sites in the network must be selected or, if such sites are impractical, alternative sites approved by the EPA Regional Administrator may be selected.
3.3.1.1 In determining the number of collocated sites required for PM 10, monitoring networks for lead (Pb) should be treated independently from networks for particulate matter (PM), even though the separate networks may share one or more common samplers. However, a single pair of samplers collocated at a common-sampler monitoring site that meets the requirements for both a collocated Pb site and a collocated PM site may serve as a collocated site for both networks.
3.3.1.2 The two collocated monitors must be within 4 meters of each other and at least 2 meters apart for flow rates greater than 200 liters/min or at least 1 meter apart for samplers having flow rates less than 200 liters/min to preclude airflow interference. Calibration, sampling, analysis and verification/validation procedures must be the same for both collocated samplers and the same as for all other samplers in the network.
3.3.1.3 For each pair of collocated samplers, designate one sampler as the primary sampler whose samples will be used to report air quality for the site, and designate the other as the audit sampler. Sample SLAMS sites on a 12-day schedule; sample PSD sites on a 6-day schedule or every third day for PSD daily samplers. If a primary quality assurance organization has only one collocated monitor, higher sampling frequencies than the 12-day schedule may be needed in order to produce approximately 25 valid sample pairs a year. Report the measurements from both samplers at each collocated sampling site. The calculations for evaluating precision between the two collocated samplers are described in section 4.2.1 of this appendix.
3.3.2 Flow Rate Verification for Particulate Matter. Follow the same procedure as described in section 3.2.3 of this appendix for PM 2.5, PM 10 (low-volume instruments), and PM 10-2.5. High-volume PM 10 and TSP instruments can also follow the procedure in section 3.2.3 but the audits are required to be conducted quarterly. The percent differences between the audit and measured flow rates are used to assess the bias of the monitoring data as described in section 4.2.2 of this appendix.
3.3.3 Semi-Annual Flow Rate Audit for Particulate Matter. Follow the same procedure as described in section 3.2.4 of this appendix for PM 2.5, PM 10, PM 10-2.5 and TSP instruments. The percent differences between these flow rates are used to validate the one-point flow rate verification checks used to estimate bias as described in section 4.2.3 of this appendix. Great care must be used in auditing high-volume particulate matter samplers having flow regulators because the introduction of resistance plates in the audit flow standard device can cause abnormal flow patterns at the point of flow sensing. For this reason, the flow audit standard should be used with a normal filter in place and without resistance plates in auditing flow-regulated high-volume samplers, or other steps should be taken to assure that flow patterns are not perturbed at the point of flow sensing.
3.3.4 Pb Methods.
3.3.4.1 Flow Rates. For the Pb Reference Methods (40 CFR Part 50, appendix G and appendix Q) and associated FEMs, the flow rates of the Pb samplers shall be verified and audited using the same procedures described in sections 3.3.2 and 3.3.3 of this appendix.
3.3.4.2 Pb Analysis Audits. Each calendar quarter or sampling quarter (PSD), audit the Pb Reference Method analytical procedure using filters containing a known quantity of Pb. These audit filters are prepared by depositing a Pb solution on unexposed filters and allowing them to dry thoroughly. The audit samples must be prepared using batches of reagents different from those used to calibrate the Pb analytical equipment being audited. Prepare audit samples in the following concentration ranges: ------------------------------------------------------------------------
Equivalent ambient Pb concentration, g/m\3\------------------------------------------------------------------------1........................ 30-100% of Pb NAAQS.2........................ 200-300% of Pb NAAQS.------------------------------------------------------------------------
(a) Audit samples must be extracted using the same extraction procedure used for exposed filters.
(b) Analyze three audit samples in each of the two ranges each quarter samples are analyzed. The audit sample analyses shall be distributed as much as possible over the entire calendar quarter.
(c) Report the audit concentrations (in g Pb/filter or strip) and the corresponding measured concentrations (in g Pb/filter or strip) using AQS unit code 077. The percent differences between the concentrations are used to calculate analytical accuracy as described in section 4.1.3 of this appendix.
(d) The audits of an equivalent Pb method are conducted and assessed in the same manner as for the reference method. The flow auditing device and Pb analysis audit samples must be compatible with the specific requirements of the equivalent method.
3.3.4.3 Collocated Sampling. PQAO that have a combination of source and non-source-oriented sites (unless the only non-source-oriented site is an NCore site) will follow the procedures described in sections 3.3.1 of this appendix with the exception that the first collocated Pb site selected must be the site measuring the highest Pb concentrations in the network. If the site is impractical, alternative sites, approved by the EPA Regional Administrator, may be selected. If additional collocated sites are necessary, collocated sites may be chosen that reflect average ambient air Pb concentrations in the network. The collocated sampling requirements for PQAO that only have Pb monitoring at a non-source-oriented NCore site for sampling required under 40 CFR 58, Appendix D, paragraph 4.5(b) shall be implemented as described in section 3.2.6 of this appendix with the exception that the collocated monitor will be the same method designation as the primary monitor.
3.3.4.4 Pb Performance Evaluation Program (PEP) Procedures. Each year, one performance evaluation audit, as described in section 3.2.7 of this appendix, must be performed at one Pb site in each primary quality assurance organization that has less than or equal to 5 sites and two audits at primary quality assurance organizations with greater than 5 sites. In addition, each year, four collocated samples from primary quality assurance organizations with less than or equal to 5 sites and six collocated samples at primary quality assurance organizations with greater than 5 sites must be sent to an independent laboratory, the same laboratory as the performance evaluation audit, for analysis.
3.3.5 Collocated Sampling Procedures for PM 2.5. Follow the same procedure as described in section 3.2.5 of this appendix. PM 2.5 samplers used in the PM 10-2.5 network, may be counted along with the PM 2.5 samplers in the PM 2.5 network as long as the PM 2.5 samplers in both networks are the same method designation.
3.3.6 Collocated Sampling Procedures for PM 10-2.5. All designated FRMs within the PM 10-2.5 monitoring network must have 15 percent of the monitors collocated (values of 0.5 and greater round up) at the PM 10-2.5 sites. All FRM method designations can be aggregated.
3.3.6.1 The EPA shall ensure that each designated FEM within the PM 10-2.5 monitoring network must:
(a) Have 15 percent of the monitors collocated (values of 0.5 and greater round up); and
(b) Have at least 2 collocated monitors (if the total number of monitors is less than 10). The first collocated monitor must be a designated FRM monitor and the second must be a monitor of the same method designation. Both collocated FRM and FEM monitors can be located at the same site.
3.3.6.2 The Regional Administrator for the EPA Region where the FRM or FEMs are implemented will select the sites for collocated monitoring. The collocation site selection process shall consider sites at primary quality assurance organizations or States with more than one PM 10-2.5 site; primary quality assurance organizations already monitoring for PM 10 and PM 2.5 using FRMs or FEMs; and an appropriate distribution among rural and urban NCore sites. Monitoring organizations implementing PM 10 samplers and PM 2.5 FRM samplers of the same method designation as the PM 10-2.5 FRM can include the PM 10-2.5 monitors in their respective PM 10 and PM 2.5 count. Follow the same procedures as described in sections 3.2.6.2 and 3.2.6.3 of this appendix.
3.3.7 PM 2.5 Performance Evaluation Program (PEP) Procedures. Follow the same procedure as described in section 3.2.7 of this appendix.
3.3.8 PM 10-2.5 Performance Evaluation Program (PEP) Procedures. One performance evaluation audit, as described in section 3.2.7 of this appendix must be performed at one PM 10-2.5 site in each primary quality assurance organization each year. Monitoring organizations implementing PM 2.5 FRM samplers of the same method designation in both the PM 2.5 and the PM 10-2.5 networks can include the PM 10-2.5 performance evaluation audit in their respective PM 2.5 performance evaluation count as long as the performance evaluation is conducted at the PM 10-2.5 site. The calculations for evaluating bias between the primary monitor(s) and the performance evaluation monitors for PM 10-2.5 are described in section 4.1.3 of this appendix.
4. Calculations for Data Quality Assessment
(a) Calculations of measurement uncertainty are carried out by EPA according to the following procedures. Primary quality assurance organizations should report the data for all appropriate measurement quality checks as specified in this appendix even though they may elect to perform some or all of the calculations in this section on their own.
(b) The EPA will provide annual assessments of data quality aggregated by site and primary quality assurance organization for SO2, NO2, O3 and CO and by primary quality assurance organization for PM 10, PM 2.5, PM 10-2.5 and Pb.
(c) At low concentrations, agreement between the measurements of collocated samplers, expressed as relative percent difference or percent difference, may be relatively poor. For this reason, collocated measurement pairs are selected for use in the precision and bias calculations only when both measurements are equal to or above the following limits:
(1) TSP: 20 g/m\3\.
(2) Pb: 0.02 g/m\3\.
(3) PM 10 (Hi-Vol): 15 g/m\3\.
(4) PM 10 (Lo-Vol): 3 g/m\3\.
(5) PM 10-2.5 and PM 2.5: 3 g/m\3\.
4.1 Statistics for the Assessment of QC Checks for SO2, NO2, O3 and CO.
4.1.1 Percent Difference. All measurement quality checks start with a comparison of an audit concentration or value (flowrate) to the concentration/value measured by the analyzer and use percent difference as the comparison statistic as described in equation 1 of this section. For each single point check, calculate the percent difference, di, as follows:[GRAPHIC] [TIFF OMITTED] TR17OC06.041 where, meas is the concentration indicated by the monitoring
organization's instrument and audit is the audit concentration
of the standard used in the QC check being measured.
4.1.2 Precision Estimate. The precision estimate is used to assess the one-point QC checks for SO2, NO2, O3, or CO described in section 3.2.1 of this appendix. The precision estimator is the coefficient of variation upper bound and is calculated using equation 2 of this section:[GRAPHIC] [TIFF OMITTED] TR17OC06.042 where, X\2\0.1,n-1 is the 10th percentile of a chi-squared
distribution with n-1 degrees of freedom.
4.1.3 Bias Estimate. The bias estimate is calculated using the one-point QC checks for SO2, NO2, O3, or CO described in section 3.2.1 of this appendix and the performance evaluation program for PM 10-2.5 described in sections 3.2.8 and 3.3.8 of this appendix. The bias estimator is an upper bound on the mean absolute value of the percent differences as described in equation 3 of this section:[GRAPHIC] [TIFF OMITTED] TR17OC06.043 where, n is the number of single point checks being aggregated;
t0.95,n-1 is the 95th quantile of a t-distribution
with n-1 degrees of freedom; the quantity AB is the mean of
the absolute values of the di's and is calculated using
equation 4 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.044
and the quantity AS is the standard deviation of the absolute value of
the di's and is calculated using equation 5 of this section:
[GRAPHIC] [TIFF OMITTED] TR17OC06.045
4.1.3.1 Assigning a sign (positive/negative) to the bias estimate. Since the bias statistic as calculated in equation 3 of this appendix uses absolute values, it does not have a tendency (negative or positive bias) associated with it. A sign will be designated by rank ordering the percent differences of the QC check samples from a given site for a particular assessment interval.
4.1.3.2 Calculate the 25th and 75th percentiles of the percent differences for each site. The absolute bias upper bound should be flagged as positive if both percentiles are positive and negative if both percentiles are negative. The absolute bias upper bound would not be flagged if the 25th and 75th percentiles are of different signs.
4.1.4 Validation of Bias Using the one-point QC Checks. The annual performance evaluations for SO2, NO2, O3, or CO described in section 3.2.2 of this appendix are used to verify the results obtained from the one-point QC checks and to validate those results across a range of concentration levels. To quantify this annually at the site level and at the 3-year primary quality assurance organization level, probability limits will be calculated from the one-point QC checks using equations 6 and 7 of this appendix:[GRAPHIC] [TIFF OMITTED] TR17OC06.064 [GRAPHIC] [TIFF OMITTED] TR41AD07.006 where, m is the mean (equation 8 of this appendix):[GRAPHIC] [TIFF OMITTED] TR17OC06.046 where, k is the total number of one point QC checks for the interval
being evaluated and S is the standard deviation of the percent
differences (equation 9 of this appendix) as follows:
[GRAPHIC] [TIFF OMITTED] TR17OC06.047
4.1.5 Percent Difference. Percent differences for the performance evaluations, calculated using equation 1 of this appendix can be compared to the probability intervals for the respective site or at the primary quality assurance organization level. Ninety-five percent of the individual percent differences (all audit concentration levels) for the performance evaluations should be captured within the probability intervals for the primary quality assurance organization.
4.2 Statistics for the Assessment of PM 10.
4.2.1 Precision Estimate from Collocated Samplers. Precision is estimated via duplicate measurements from collocated samplers of the same type. It is recommended that the precision be aggregated at the primary quality assurance organization level quarterly, annually, and at the 3-year level. The data pair would only be considered valid if both concentrations are greater than the minimum values specified in section 4(c) of this appendix. For each collocated data pair, calculate the relative percent difference, di, using equation 10 of this appendix: [GRAPHIC] [TIFF OMITTED] TR17OC06.048 where, Xi is the concentration from the primary sampler and Yi is the
concentration value from the audit sampler. The coefficient of
variation upper bound is calculated using the equation 11 of
this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.049
where, n is the number of valid data pairs being aggregated, and X\2\
0.1, n-1 is the 10th percentile of a chi-squared
distribution with n-1 degrees of freedom. The factor of 2 in
the denominator adjusts for the fact that each di
is calculated from two values with error. 4.2.2 Bias Estimate Using One-Point Flow Rate Verifications. For each
one-point flow rate verification described in sections 3.2.3
and 3.3.2 of this appendix, calculate the percent difference
in volume using equation 1 of this appendix where meas is the
value indicated by the sampler's volume measurement and audit
is the actual volume indicated by the auditing flow meter. The
absolute volume bias upper bound is then calculated using
equation 3, where n is the number of flow rate audits being
aggregated; t0.95,n-1 is the 95th quantile of a t-
distribution with n-1 degrees of freedom, the quantity AB is
the mean of the absolute values of the di's and is calculated
using equation 4 of this appendix , and the quantity AS in
equation 3 of this appendix is the standard deviation of the
absolute values if the di's and is calculated using equation 5
of this
4.2.3 Assessment Semi-Annual Flow Rate Audits. The flow rate audits described in sections 3.2.4 and 3.3.3 of this appendix are used to assess the results obtained from the one-point flow rate verifications and to provide an estimate of flow rate acceptability. For each flow rate audit, calculate the percent difference in volume using equation 1 of this appendix where meas is the value indicated by the sampler's volume measurement and audit is the actual volume indicated by the auditing flow meter. To quantify this annually and at the 3-year primary quality assurance organization level, probability limits are calculated from the percent differences using equations 6 and 7 of this appendix where m is the mean described in equation 8 of this appendix and k is the total number of one-point flow rate verifications for the year and S is the standard deviation of the percent differences as described in equation 9 of this appendix.
4.2.4 Percent Difference. Percent differences for the annual flow rate audit concentration, calculated using equation 1 of this appendix, can be compared to the probability intervals for the one-point flow rate verifications for the respective primary quality assurance organization. Ninety-five percent of the individual percent differences (all audit concentration levels) for the performance evaluations should be captured within the probability intervals for primary quality assurance organization.
4.3 Statistics for the Assessment of PM 2.5 and PM 10-2.5.
4.3.1 Precision Estimate. Precision for collocated instruments for PM 2.5 and PM 10-2.5 may be estimated where both the primary and collocated instruments are the same method designation and when the method designations are not similar. Follow the procedure described in section 4.2.1 of this appendix. In addition, one may want to perform an estimate of bias when the primary monitor is an FEM and the collocated monitor is an FRM. Follow the procedure described in section 4.1.3 of this appendix in order to provide an estimate of bias using the collocated data.
4.3.2 Bias Estimate. Follow the procedure described in section 4.1.3 of this appendix for the bias estimate of PM 10-2.5. The PM 2.5 bias estimate is calculated using the paired routine and the PEP monitor data described in section 3.2.6 of this appendix. Calculate the percent difference, di, using equation 1 of this appendix, where meas is the measured concentration from agency's primary monitor and audit is the concentration from the PEP monitor. The data pair would only be considered valid if both concentrations are greater than the minimum values specified in section 4(c) of this appendix. Estimates of bias are presented for various levels of aggregation, sometimes aggregating over time, sometimes aggregating over samplers, and sometimes aggregating over both time and samplers. These various levels of aggregation are achieved using the same basic statistic.
4.3.2.1 This statistic averages the individual biases described in equation 1 of this appendix to the desired level of aggregation using equation 12 of this appendix:[GRAPHIC] [TIFF OMITTED] TR17OC06.050 where, nj is the number of pairs and d1, d2, * *
*, dnj are the biases for each of the pairs to be averaged.
4.3.2.2 Confidence intervals can be constructed for these average bias estimates in equation 12 of this appendix using equations 13 and 14 of this appendix:[GRAPHIC] [TIFF OMITTED] TR17OC06.051 [GRAPHIC] [TIFF OMITTED] TR17OC06.052 Where, t0.95,df is the 95th quantile of a t-distribution with
degrees of freedom df = nj - 1 and s is an estimate
of the variability of the average bias calculated using
equation 15 of this appendix:
[GRAPHIC] [TIFF OMITTED] TR17OC06.053
4.4 Statistics for the Assessment of Pb.
4.4.1 Precision Estimate. Follow the same procedures as described for PM 10 in section 4.2.1 of this appendix using the data from the collocated instruments. The data pair would only be considered valid if both concentrations are greater than the minimum values specified in section 4(c) of this appendix.
4.4.2 Bias Estimate. For the Pb analysis audits described in section 3.3.4.2 and the Pb Performance Evaluation Program described in section 3.3.4.4, follow the same procedure as described in section 4.1.3 for the bias estimate.
4.4.3 Flow rate calculations. For the one point flow rate verifications, follow the same procedures as described for PM 10 in section 4.2.2; for the flow rate audits, follow the same procedures as described in section 4.2.3.
5. Reporting Requirements
5.1 SLAMS Reporting Requirements. For each pollutant, prepare a list of all monitoring sites and their AQS site identification codes in each primary quality assurance organization and submit the list to the appropriate EPA Regional Office, with a copy to AQS. Whenever there is a change in this list of monitoring sites in a primary quality assurance organization, report this change to the EPA Regional Office and to AQS.
5.1.1 Quarterly Reports. For each quarter, each primary quality assurance organization shall report to AQS directly (or via the appropriate EPA Regional Office for organizations not direct users of AQS) the results of all valid measurement quality checks it has carried out during the quarter. The quarterly reports must be submitted consistent with the data reporting requirements specified for air quality data as set forth in Sec. 58.16. The EPA strongly encourages early submission of the quality assurance data in order to assist the monitoring organizations control and evaluate the quality of the ambient air data.
5.1.2 Annual Reports.
5.1.2.1 When the monitoring organization has certified relevant data for the calendar year, EPA will calculate and report the measurement uncertainty for the entire calendar year.
5.2 PSD Reporting Requirements. At the end of each sampling quarter, the organization must report the appropriate statistical assessments in section 4 of this appendix for the pollutants measured. All data used to calculate reported estimates of precision and bias including span checks, collocated sampler and audit results must be made available to the permit granting authority upon request.
6.0 References
(1) American National Standard--Specifications and Guidelines for Quality Systems for Environmental Data Collection and Environmental Technology Programs. ANSI/ASQC E4-2004. February 2004. Available from American Society for Quality Control, 611 East Wisconsin Avenue, Milwaukee, WI 53202.
(2) EPA Requirements for Quality Management Plans. EPA QA/R-2. EPA/240/B-01/002. March 2001. Office of Environmental Information, Washington DC 20460. http://www.epa.gov/quality/qs-docs/r2-final.pdf.
(3) EPA Requirements for Quality Assurance Project Plans for Environmental Data Operations. EPA QA/R-5. EPA/240/B-01/003. March 2001. Office of Environmental Information, Washington DC 20460. http://www.epa.gov/quality/qs-docs/r5-final.pdf.
(4) EPA Traceability Protocol for Assay and Certification of Gaseous Calibration Standards. EPA-600/R-97/121. September 1997. Available from U.S. Environmental Protection Agency, ORD Publications Office, Center for Environmental Research Information (CERI), 26 W. Martin Luther King Drive, Cincinnati, OH 45268.
(5) Guidance for the Data Quality Objectives Process. EPA QA/G-4. EPA/240/B-06/001. February, 2006. Office of Environmental Information, Washington DC 20460. http://www.epa.gov/quality/qs-docs/g4-final.pdf.
(6) List of Designated Reference and Equivalent Methods. Available from U.S. Environmental Protection Agency, National Exposure Research Laboratory, Human Exposure and Atmospheric Sciences Division, MD-D205-03, Research Triangle Park, NC 27711. http://www.epa.gov/ttn/amtic/criteria.html.
(7) McElroy, F.F. Transfer Standards for the Calibration of Ambient Air Monitoring Analyzers for Ozone. EPA-600/4-79-056. U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, September, 1979. http://www.epa.gov/ttn/amtic/cpreldoc.html.
(8) Paur, R.J. and F.F. McElroy. Technical Assistance Document for the Calibration of Ambient Ozone Monitors. EPA-600/4-79-057. U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, September, 1979. http://www.epa.gov/ttn/amtic/cpreldoc.html.
(9) Quality Assurance Handbook for Air Pollution Measurement Systems, Volume 1--A Field Guide to Environmental Quality Assurance. EPA-600/R-94/038a. April 1994. Available from U.S. Environmental Protection Agency, ORD Publications Office, Center for Environmental Research Information (CERI), 26 W. Martin Luther King Drive, Cincinnati, OH 45268. http://www.epa.gov/ttn/amtic/qabook.html.
(10) Quality Assurance Handbook for Air Pollution Measurement Systems, Volume II: Part 1--Ambient Air Quality Monitoring Program Quality System Development. EPA-454/R-98-004. http://www.epa.gov/ttn/amtic/qabook.html.
Table A-1 of Appendix A to Part 58--Difference and Similarities Between
SLAMS and PSD Requirements------------------------------------------------------------------------
Topic SLAMS PSD------------------------------------------------------------------------Requirements.................... 1. The Same as SLAMS.
development,
documentation,
and
implementation of
an approved
quality system.
2. The assessment
of data quality.
3. The use of
reference,
equivalent, or
approved methods.
4. The use of
calibration
standards
traceable to NIST
or other primary
standard.
5. The Same as SLAMS
participation in
EPA performance
evaluations and
the permission
for EPA to
conduct system
audits.Monitoring and QA Responsibility State/local agency Source owner/
via the ``primary operator.
quality assurance
organization''.Monitoring Duration............. Indefinitely...... Usually up to 12
months.Annual Performance Evaluation Standards and Personnel,
(PE). equipment standards and
different from equipment
those used for different from
spanning, those used for
calibration, and spanning,
verifications. calibration, and
Prefer different verifications.
personnel.PE audit rate:
--Automated................. 100% per year..... 100% per quarter.
--Manual.................... Varies depending 100% per quarter.
on pollutant. See
Table A-2 of this
appendix.Precision Assessment:
--Automated................. One-point QC check One point QC check
biweekly but data biweekly.
quality dependent.
--Manual.................... Varies depending One site: 1 every
on pollutant. See 6 days or every
Table A-2 of this third day for
appendix. daily monitoring
(TSP and Pb).Reporting
--Automated................. By site--EPA By site--source
performs owner/operator
calculations performs
annually. calculations each
sampling quarter.
--Manual.................... By reporting By site--source
organization--EPA owner/operator
performs performs
calculations calculations each
annually. sampling quarter.------------------------------------------------------------------------
Table A-2 of Appendix A to Part 58--Minimum Data Assessment Requirements for SLAMS Sites----------------------------------------------------------------------------------------------------------------
Parameters
Method Assessment method Coverage Minimum frequency reported----------------------------------------------------------------------------------------------------------------
Automated Methods----------------------------------------------------------------------------------------------------------------1-Point QC for SO2, NO2, O3, CO. Response check at Each analyzer..... Once per 2 weeks.. Audit
concentration concentration \1\
0.01-0.1 ppm SO2, and measured
NO2, O3, and 1-10 concentration
ppm CO. \2\.Annual performance evaluation See section 3.2.2 Each analyzer..... Once per year..... Audit
for SO2, NO2, O3, CO. of this appendix. concentration \1\
and measured
concentration \2\
for each level.Flow rate verification PM 10, PM Check of sampler Each sampler...... Once every month.. Audit flow rate
2.5, PM 10 2.5. flow rate. and measured flow
rate indicated by
the sampler.Semi-annual flow rate audit PM Check of sampler Each sampler...... Once every 6 Audit flow rate
10, PM 2.5, PM 10 2.5. flow rate using months. and measured flow
independent rate indicated by
standard. the sampler.Collocated sampling PM 2.5, PM Collocated 15%............... Every 12 days..... Primary sampler
10 2.5. samplers. concentration and
duplicate sampler
concentration.Performance evaluation program Collocated 1. 5 valid audits Over all 4 Primary sampler
PM 2.5, PM 10 2.5. samplers. for primary QA quarters. concentration and
orgs, with 45 performance
sites. evaluation
2. 8 valid audits sampler
for primary QA concentration.
orgs, with >5
sites.
3. All samplers in
6 years.----------------------------------------------------------------------------------------------------------------
Manual Methods----------------------------------------------------------------------------------------------------------------Collocated sampling PM 10, TSP, Collocated 15%............... Every 12 days PSD-- Primary sampler
PM 10 2.5, PM 2.5, Pb-TSP, Pb- samplers. every 6 days. concentration and
PM 10. duplicate sampler
concentration.Flow rate verification PM 10 Check of sampler Each sampler...... Once every month.. Audit flow rate
(low Vol), PM 10 2.5, PM 2.5, flow rate. and measured flow
Pb-PM 10. rate indicated by
the sampler.Flow rate verification PM 10 Check of sampler Each sampler...... Once every quarter Audit flow rate
(High-Vol), TSP, Pb-TSP. flow rate. and measured flow
rate indicated by
the sampler.Semi-annual flow rate audit PM Check of sampler Each sampler, all Once every 6 Audit flow rate
10, TSP, PM 10 2.5, PM 2.5, Pb- flow rate using locations. months. and measured flow
TSP, Pb-PM 10. independent rate indicated by
standard. the sampler.Pb audit strips Pb-TSP, Pb-PM 10 Check of Analytical........ Each quarter...... Actual
analytical system concentration and
with Pb audit audit
strips. concentration.Performance evaluation program Collocated 1. 5 valid audits Over all 4 Primary sampler
PM 2.5, PM 10 2.5. samplers. for primary QA quarters. concentration and
orgs, with 45 performance
sites. evaluation
2. 8 valid audits sampler
for primary QA concentration.
orgs, with >5
sites.
3. All samplers in
6 years.
Performance evaluation program Collocated 1. 1 valid audit Over all 4 Primary sampler
Pb-TSP, Pb-PM 10. samplers. and 4 collocated quarters. concentration and
samples for performance
primary QA orgs, evaluation
with >5 sites. sampler
2. 2 valid audits concentration.
and 6 collocated Primary sampler
samples for concentration and
primary QA orgs, duplicate sampler
with >5 sites. concentration.----------------------------------------------------------------------------------------------------------------\1\ Effective concentration for open path analyzers.\2\ Corrected concentration, if applicable, for open path analyzers.
Table A-3 of Appendix A to Part 58--Summary of PM 2.5 Number and Type of Collocation (15% Collocation
Requirement) Needed as an Example of a Primary Quality Assurance Organization That Has 54 Monitors and Procured
FRMs and Three Other Equivalent Method Types----------------------------------------------------------------------------------------------------------------
No. of
collocated
Total no. of Total no. No. of monitors of
Primary sampler method designation monitors collocated collocated FRM same method
designation as
primary----------------------------------------------------------------------------------------------------------------FRM............................................. 20 3 3 n/aFEM (A)......................................... 20 3 2 1FEM (C)......................................... 2 1 1 0FEM (D)......................................... 12 2 1 1---------------------------------------------------------------------------------------------------------------- [71 FR 61303, Oct. 17, 2006, as amended at 72 FR 32211, June 12, 2007; 73 FR 67060, Nov. 12, 2008; 75 FR 6534, Feb. 9, 2010; 75 FR 35602, June 22, 2010; 75 FR 81137, Dec. 27, 2010; 78 FR 3283, Jan. 15, 2013]
Editorial Note: At 72 FR 32211, June 13, 2007, the last sentence in section 4.2.2.2, was amended in Appendix A to Part 58; however, the amendment could not be incorporated due to inaccurate amendatory instruction.
Sec. Appendix B to Part 58 [Reserved]
Sec. Appendix C to Part 58--Ambient Air Quality Monitoring Methodology 1.0 Purpose2.0 SLAMS Ambient Air Monitoring Stations3.0 NCore Ambient Air Monitoring Stations4.0 Photochemical Assessment Monitoring Stations (PAMS)5.0 Particulate Matter Episode Monitoring6.0 References
1.0 Purpose
This appendix specifies the criteria pollutant monitoring methods (manual methods or automated analyzers) which must be used in SLAMS and NCore stations that are a subset of SLAMS.
2.0 SLAMS Ambient Air Monitoring Network
2.1 Except as otherwise provided in this appendix, a criteria pollutant monitoring method used for making NAAQS decisions at a SLAMS site must be a reference or equivalent method as defined in Sec. 50.1 of this chapter.
2.1.1 Any NO2 FRM or FEM used for making primary NAAQS decisions must be capable of providing hourly averaged concentration data.
2.2 Reserved
2.3 Any manual method or analyzer purchased prior to cancellation of its reference or equivalent method designation under Sec. 53.11 or Sec. 53.16 of this chapter may be used at a SLAMS site following cancellation for a reasonable period of time to be determined by the Administrator.
2.4 Approval of Non-designated Continuous PM 2.5 Methods as Approved Regional Methods (ARMs) Operated Within a Network of Sites. A method for PM 2.5 that has not been designated as an FRM or FEM as defined in Sec. 50.1 of this chapter may be approved as an ARM for purposes of section 2.1 of this appendix at a particular site or network of sites under the following stipulations.
2.4.1 The candidate ARM must be demonstrated to meet the requirements for PM 2.5 Class III equivalent methods as defined in subpart C of part 53 of this chapter. Specifically the requirements for precision, correlation, and additive and multiplicative bias apply. For purposes of this section 2.4, the following requirements shall apply:
2.4.1.1 The candidate ARM shall be tested at the site(s) in which it is intended to be used. For a network of sites operated by one reporting agency or primary quality assurance organization, the testing shall occur at a subset of sites to include one site in each MSA/CSA, up to the first 2 highest population MSA/CSA and at least one rural area or Micropolitan Statistical Area site. If the candidate ARM for a network is already approved for purposes of this section in another agency's network, subsequent testing shall minimally occur at one site in a MSA/CSA and one rural area or Micropolitan Statistical Area. There shall be no requirement for tests at any other sites.
2.4.1.2 For purposes of this section, a full year of testing may begin and end in any season, so long as all seasons are covered.
2.4.1.3 No PM 10 samplers shall be required for the test, as determination of the PM 2.5/PM 10 ratio at the test site shall not be required.
2.4.1.4 The test specification for PM 2.5 Class III equivalent method precision defined in subpart C of part 53 of this chapter applies; however, there is no specific requirement that collocated continuous monitors be operated for purposes of generating a statistic for coefficient of variation (CV). To provide an estimate of precision that meets the requirement identified in subpart C of part 53 of this chapter, agencies may cite peer-reviewed published data or data in AQS that can be presented demonstrating the candidate ARM operated will produce data that meets the specification for precision of Class III PM 2.5 methods.
2.4.1.5 A minimum of 90 valid sample pairs per site for the year with no less than 20 valid sample pairs per season must be generated for use in demonstrating that additive bias, multiplicative bias and correlation meet the comparability requirements specified in subpart C of part 53 of this chapter. A valid sample pair may be generated with as little as one valid FRM and one valid candidate ARM measurement per day.
2.4.1.6 For purposes of determining bias, FRM data with concentrations less than 3 micrograms per cubic meter (g/m\3\) may be excluded. Exclusion of data does not result in failure of sample completeness specified in this section.
2.4.1.7 Data transformations are allowed to be used to demonstrate meeting the comparability requirements specified in subpart C of part 53 of this chapter. Data transformation may be linear or non-linear, but must be applied in the same way to all sites used in the testing.
2.4.2 The monitoring agency wishing to use an ARM must develop and implement appropriate quality assurance procedures for the method. Additionally, the following procedures are required for the method:
2.4.2.1 The ARM must be consistently operated throughout the network. Exceptions to a consistent operation must be approved according to section 2.8 of this appendix;
2.4.2.2 The ARM must be operated on an hourly sampling frequency capable of providing data suitable for aggregation into daily 24-hour average measurements;
2.4.2.3 The ARM must use an inlet and separation device, as needed, that are already approved in either the reference method identified in appendix L to part 50 of this chapter or under part 53 of this chapter as approved for use on a PM 2.5 reference or equivalent method. The only exceptions to this requirement are those methods that by their inherent measurement principle may not need an inlet or separation device that segregates the aerosol; and
2.4.2.4 The ARM must be capable of providing for flow audits, unless by its inherent measurement principle, measured flow is not required. These flow audits are to be performed on the frequency identified in appendix A to this part.
2.4.2.5 If data transformations are used, they must be described in the monitoring agencies Quality Assurance Project plan (or addendum to QAPP). The QAPP shall describe how often (e.g., quarterly, yearly) and under what provisions the data transformation will be updated. For example, not meeting the data quality objectives for a site over a season or year may be cause for recalculating a data transformation, but by itself would not be cause for invalidating the data. Data transformations must be applied prospectively, i.e., in real-time or near real-time, to the data output from the PM 2.5 continuous method. See reference 7 of this appendix.
2.4.3 The monitoring agency wishing to use the method must develop and implement appropriate procedures for assessing and reporting the precision and accuracy of the method comparable to the procedures set forth in appendix A of this part for designated reference and equivalent methods.
2.4.4 Assessments of data quality shall follow the same frequencies and calculations as required under section 3 of appendix A to this part with the following exceptions:
2.4.4.1 Collocation of ARM with FRM/FEM samplers must be maintained at a minimum of 30 percent of the required SLAMS sites with a minimum of 1 per network;
2.4.4.2 All collocated FRM/FEM samplers must maintain a sample frequency of at least 1 in 6 sample days;
2.4.4.3 Collocated FRM/FEM samplers shall be located at the design value site, with the required FRM/FEM samplers deployed among the largest MSA/CSA in the network, until all required FRM/FEM are deployed; and
2.4.4.4 Data from collocated FRM/FEM are to be substituted for any calendar quarter that an ARM method has incomplete data.
2.4.4.5 Collocation with an ARM under this part for purposes of determining the coefficient of variation of the method shall be conducted at a minimum of 7.5 percent of the sites with a minimum of 1 per network. This is consistent with the requirements in appendix A to this part for one-half of the required collocation of FRM/FEM (15 percent) to be collocated with the same method.
2.4.4.6 Assessments of bias with an independent audit of the total measurement system shall be conducted with the same frequency as an FEM as identified in appendix A to this part.
2.4.5 Request for approval of a candidate ARM, that is not already approved in another agency's network under this section, must meet the general submittal requirements of section 2.7 of this appendix. Requests for approval under this section when an ARM is already approved in another agency's network are to be submitted to the EPA Regional Administrator. Requests for approval under section 2.4 of this appendix must include the following requirements:
2.4.5.1 A clear and unique description of the site(s) at which the candidate ARM will be used and tested, and a description of the nature or character of the site and the particulate matter that is expected to occur there.
2.4.5.2 A detailed description of the method and the nature of the sampler or analyzer upon which it is based.
2.4.5.3 A brief statement of the reason or rationale for requesting the approval.
2.4.5.4 A detailed description of the quality assurance procedures that have been developed and that will be implemented for the method.
2.4.5.5 A detailed description of the procedures for assessing the precision and accuracy of the method that will be implemented for reporting to AQS.
2.4.5.6 Test results from the comparability tests as required in section 2.4.1 through 2.4.1.4 of this appendix.
2.4.5.7 Such further supplemental information as may be necessary or helpful to support the required statements and test results.
2.4.6 Within 120 days after receiving a request for approval of the use of an ARM at a particular site or network of sites under section 2.4 of this appendix, the Administrator will approve or disapprove the method by letter to the person or agency requesting such approval. When appropriate for methods that are already approved in another SLAMS network, the EPA Regional Administrator has approval/disapproval authority. In either instance, additional information may be requested to assist with the decision.
2.5 [Reserved]
2.6 Use of Methods With Higher, Nonconforming Ranges in Certain Geographical Areas.
2.6.1 [Reserved]
2.6.2 An analyzer may be used (indefinitely) on a range which extends to concentrations higher than two times the upper limit specified in table B-1 of part 53 of this chapter if:
2.6.2.1 The analyzer has more than one selectable range and has been designated as a reference or equivalent method on at least one of its ranges, or has been approved for use under section 2.5 (which applies to analyzers purchased before February 18, 1975);
2.6.2.2 The pollutant intended to be measured with the analyzer is likely to occur in concentrations more than two times the upper range limit specified in table B-1 of part 53 of this chapter in the geographical area in which use of the analyzer is proposed; and
2.6.2.3 The Administrator determines that the resolution of the range or ranges for which approval is sought is adequate for its intended use. For purposes of this section (2.6), ``resolution'' means the ability of the analyzer to detect small changes in concentration.
2.6.3 Requests for approval under section 2.6.2 of this appendix must meet the submittal requirements of section 2.7. Except as provided in section 2.7.3 of this appendix, each request must contain the information specified in section 2.7.2 in addition to the following:
2.6.3.1 The range or ranges proposed to be used;
2.6.3.2 Test data, records, calculations, and test results as specified in section 2.7.2.2 of this appendix for each range proposed to be used;
2.6.3.3 An identification and description of the geographical area in which use of the analyzer is proposed;
2.6.3.4 Data or other information demonstrating that the pollutant intended to be measured with the analyzer is likely to occur in concentrations more than two times the upper range limit specified in table B-1 of part 53 of this chapter in the geographical area in which use of the analyzer is proposed; and
2.6.3.5 Test data or other information demonstrating the resolution of each proposed range that is broader than that permitted by section 2.5 of this appendix.
2.6.4 Any person who has obtained approval of a request under this section (2.6.2) shall assure that the analyzer for which approval was obtained is used only in the geographical area identified in the request and only while operated in the range or ranges specified in the request.
2.7 Requests for Approval; Withdrawal of Approval.
2.7.1 Requests for approval under sections 2.4, 2.6.2, or 2.8 of this appendix must be submitted to: Director, National Exposure Research Laboratory (MD-D205-03), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711. For ARM that are already approved in another agency's network, subsequent requests for approval under section 2.4 are to be submitted to the applicable EPA Regional Administrator.
2.7.2 Except as provided in section 2.7.3 of this appendix, each request must contain:
2.7.2.1 A statement identifying the analyzer (e.g., by serial number) and the method of which the analyzer is representative (e.g., by manufacturer and model number); and
2.7.2.2 Test data, records, calculations, and test results for the analyzer (or the method of which the analyzer is representative) as specified in subpart B, subpart C, or both (as applicable) of part 53 of this chapter.
2.7.3 A request may concern more than one analyzer or geographical area and may incorporate by reference any data or other information known to EPA from one or more of the following:
2.7.3.1 An application for a reference or equivalent method determination submitted to EPA for the method of which the analyzer is representative, or testing conducted by the applicant or by EPA in connection with such an application;
2.7.3.2 Testing of the method of which the analyzer is representative at the initiative of the Administrator under Sec. 53.7 of this chapter; or
2.7.3.3 A previous or concurrent request for approval submitted to EPA under this section (2.7).
2.7.4 To the extent that such incorporation by reference provides data or information required by this section (2.7) or by sections 2.4, 2.5, or 2.6 of this appendix, independent data or duplicative information need not be submitted.
2.7.5 After receiving a request under this section (2.7), the Administrator may request such additional testing or information or conduct such tests as may be necessary in his judgment for a decision on the request.
2.7.6 If the Administrator determines, on the basis of any available information, that any of the determinations or statements on which approval of a request under this section was based are invalid or no longer valid, or that the requirements of section 2.4, 2.5, or 2.6, as applicable, have not been met, he/she may withdraw the approval after affording the person who obtained the approval an opportunity to submit information and arguments opposing such action.
2.8 Modifications of Methods by Users.
2.8.1 Except as otherwise provided in this section, no reference method, equivalent method, or ARM may be used in a SLAMS network if it has been modified in a manner that could significantly alter the performance characteristics of the method without prior approval by the Administrator. For purposes of this section, ``alternative method'' means an analyzer, the use of which has been approved under section 2.4, 2.5, or 2.6 of this appendix or some combination thereof.
2.8.2 Requests for approval under this section (2.8) must meet the submittal requirements of sections 2.7.1 and 2.7.2.1 of this appendix.
2.8.3 Each request submitted under this section (2.8) must include:
2.8.3.1 A description, in such detail as may be appropriate, of the desired modification;
2.8.3.2 A brief statement of the purpose(s) of the modification, including any reasons for considering it necessary or advantageous;
2.8.3.3 A brief statement of belief concerning the extent to which the modification will or may affect the performance characteristics of the method; and
2.8.3.4 Such further information as may be necessary to explain and support the statements required by sections 2.8.3.2 and 2.8.3.3.
2.8.4 The Administrator will approve or disapprove the modification by letter to the person or agency requesting such approval within 75 days after receiving a request for approval under this section and any further information that the applicant may be asked to provide.
2.8.5 A temporary modification that could alter the performance characteristics of a reference, equivalent, or ARM may be made without prior approval under this section if the method is not functioning or is malfunctioning, provided that parts necessary for repair in accordance with the applicable operation manual cannot be obtained within 45 days. Unless such temporary modification is later approved under section 2.8.4 of this appendix, the temporarily modified method shall be repaired in accordance with the applicable operation manual as quickly as practicable but in no event later than 4 months after the temporary modification was made, unless an extension of time is granted by the Administrator. Unless and until the temporary modification is approved, air quality data obtained with the method as temporarily modified must be clearly identified as such when submitted in accordance with Sec. 58.16 and must be accompanied by a report containing the information specified in section 2.8.3 of this appendix. A request that the Administrator approve a temporary modification may be submitted in accordance with sections 2.8.1 through 2.8.4 of this appendix. In such cases the request will be considered as if a request for prior approval had been made.
2.9 Use of IMPROVE Samplers at a SLAMS Site. ``IMPROVE'' samplers may be used in SLAMS for monitoring of regional background and regional transport concentrations of fine particulate matter. The IMPROVE samplers were developed for use in the Interagency Monitoring of Protected Visual Environments (IMPROVE) network to characterize all of the major components and many trace constituents of the particulate matter that impair visibility in Federal Class I Areas. Descriptions of the IMPROVE samplers and the data they collect are available in references 4, 5, and 6 of this appendix.
2.10 Use of Pb-PM10 at SLAMS Sites.
2.10.1 The EPA Regional Administrator may approve the use of a Pb-PM 10 FRM or Pb-PM 10 FEM sampler in lieu of a Pb-TSP sampler as part of the network plan required under part 58.10(a)(4) in the following cases.
2.10.1.1 Pb-PM 10 samplers can be approved for use at the non-source-oriented sites required under paragraph 4.5(b) of Appendix D to part 58 if there is no existing monitoring data indicating that the maximum arithmetic 3-month mean Pb concentration (either Pb-TSP or Pb-PM 10) at the site was equal to or greater than 0.10 micrograms per cubic meter during the previous 3 years.
2.10.1.2 Pb-PM 10 samplers can be approved for use at source-oriented sites required under paragraph 4.5(a) if the monitoring agency can demonstrate (through modeling or historic monitoring data from the last 3 years) that Pb concentrations (either Pb-TSP or Pb-PM 10) will not equal or exceed 0.10 micrograms per cubic meter on an arithmetic 3-month mean and the source is expected to emit a substantial majority of its Pb in the fraction of PM with an aerodynamic diameter of less than or equal to 10 micrometers.
2.10.2 The approval of a Pb-PM 10 sampler in lieu of a Pb-TSP sampler as allowed for in paragraph 2.10.1 above will be revoked if measured Pb-PM 10 concentrations equal or exceed 0.10 micrograms per cubic meter on an arithmetic 3-month mean. Monitoring agencies will have up to 6 months from the end of the 3-month period in which the arithmetic 3-month Pb-PM 10 mean concentration equaled or exceeded 0.10 micrograms per cubic meter to install and begin operation of a Pb-TSP sampler at the site.
3.0 NCore Ambient Air Monitoring Stations
3.1 Methods employed in NCore multipollutant sites used to measure SO2, CO, NO2, O3, PM 2.5, or PM 10-2.5 must be reference or equivalent methods as defined in Sec. 50.1 of this chapter, or an ARM as defined in section 2.4 of this appendix, for any monitors intended for comparison with applicable NAAQS.
3.2 If alternative SO2, CO, NO2, O3, PM 2.5, or PM 10-2.5 monitoring methodologies are proposed for monitors not intended for NAAQS comparison, such techniques must be detailed in the network description required by Sec. 58.10 and subsequently approved by the Administrator. Examples of locations that are not intended to be compared to the NAAQS may be rural background and transport sites or areas where the concentration of the pollutant is so low that it would be more useful to operate a higher sensitivity method that is not an FRM or FEM.
4.0 Photochemical Assessment Monitoring Stations (PAMS)
4.1 Methods used for O3 monitoring at PAMS must be automated reference or equivalent methods as defined in Sec. 50.1 of this chapter.
4.2 Methods used for NO, NO2 and NOX monitoring at PAMS should be automated reference or equivalent methods as defined for NO2 in Sec. 50.1 of this chapter. If alternative NO, NO2 or NOX monitoring methodologies are proposed, such techniques must be detailed in the network description required by Sec. 58.10 and subsequently approved by the Administrator.
4.3 Methods for meteorological measurements and speciated VOC monitoring are included in the guidance provided in references 2 and 3 of this appendix. If alternative VOC monitoring methodology (including the use of new or innovative technologies), which is not included in the guidance, is proposed, it must be detailed in the network description required by Sec. 58.10 and subsequently approved by the Administrator.
5.0 Particulate Matter Episode Monitoring
5.1 For short-term measurements of PM 10 during air pollution episodes (see Sec. 51.152 of this chapter) the measurement method must be:
5.1.1 Either the ``Staggered PM 10'' method or the ``PM 10 Sampling Over Short Sampling Times'' method, both of which are based on the reference method for PM 10 and are described in reference 1: or
5.1.2 Any other method for measuring PM 10:
5.1.2.1 Which has a measurement range or ranges appropriate to accurately measure air pollution episode concentration of PM 10,
5.1.2.2 Which has a sample period appropriate for short-term PM 10 measurements, and
5.1.2.3 For which a quantitative relationship to a reference or equivalent method for PM 10 has been established at the use site. Procedures for establishing a quantitative site-specific relationship are contained in reference 1.
5.2 PM 10 methods other than the reference method are not covered under the quality assessment requirements of appendix to this part. Therefore, States must develop and implement their own quality assessment procedures for those methods allowed under this section 4. These quality assessment procedures should be similar or analogous to those described in section 3 of appendix A to this part for the PM 10 reference method.
6.0 References
1. Pelton, D. J. Guideline for Particulate Episode Monitoring Methods, GEOMET Technologies, Inc., Rockville, MD. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-83-005. February 1983.
2. Technical Assistance Document For Sampling and Analysis of Ozone Precursors. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.
3. Quality Assurance Handbook for Air Pollution Measurement Systems: Volume IV. Meteorological Measurements. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-0003. August 1989.
4. Eldred, R.A., Cahill, T.A., Wilkenson, L.K., et al., Measurements of fine particles and their chemical components in the IMPROVE/NPS networks, in Transactions of the International Specialty Conference on Visibility and Fine Particles, Air and Waste Management Association: Pittsburgh, PA, 1990; pp. 187-196.
5. Sisler, J.F., Huffman, D., and Latimer, D.A.; Spatial and temporal patterns and the chemical composition of the haze in the United States: An analysis of data from the IMPROVE network, 1988-1991, ISSN No. 0737-5253-26, National Park Service, Ft. Collins, CO, 1993.
6. Eldred, R.A., Cahill, T.A., Pitchford, M., and Malm, W.C.; IMPROVE--a new remote area particulate monitoring system for visibility studies, Proceedings of the 81st Annual Meeting of the Air Pollution Control Association, Dallas, Paper 88-54.3, 1988.
7. Data Quality Objectives (DQOs) for Relating Federal Reference Method (FRM) and Continuous PM 2.5 Measurements to Report an Air Quality Index (AQI). Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 454/B-02-2002. November 2002. [71 FR 61313, Oct. 17, 2006, as amended at 73 FR 67061, Nov. 12, 2008; 75 FR 6534, Feb. 9, 2010]
Sec. Appendix D to Part 58--Network Design Criteria for Ambient Air
Quality Monitoring 1. Monitoring Objectives and Spatial Scales2. General Monitoring Requirements3. Design Criteria for NCore Sites4. Pollutant-Specific Design Criteria for SLAMS Sites5. Design Criteria for Photochemical Assessment Monitoring Stations
(PAMS)6. References
1. Monitoring Objectives and Spatial Scales
The purpose of this appendix is to describe monitoring objectives and general criteria to be applied in establishing the required SLAMS ambient air quality monitoring stations and for choosing general locations for additional monitoring sites. This appendix also describes specific requirements for the number and location of FRM, FEM, and ARM sites for specific pollutants, NCore multipollutant sites, PM 10 mass sites, PM 2.5 mass sites, chemically-speciated PM 2.5 sites, and O3 precursor measurements sites (PAMS). These criteria will be used by EPA in evaluating the adequacy of the air pollutant monitoring networks.
1.1 Monitoring Objectives. The ambient air monitoring networks must be designed to meet three basic monitoring objectives. These basic objectives are listed below. The appearance of any one objective in the order of this list is not based upon a prioritized scheme. Each objective is important and must be considered individually.
(a) Provide air pollution data to the general public in a timely manner. Data can be presented to the public in a number of attractive ways including through air quality maps, newspapers, Internet sites, and as part of weather forecasts and public advisories.
(b) Support compliance with ambient air quality standards and emissions strategy development. Data from FRM, FEM, and ARM monitors for NAAQS pollutants will be used for comparing an area's air pollution levels against the NAAQS. Data from monitors of various types can be used in the development of attainment and maintenance plans. SLAMS, and especially NCore station data, will be used to evaluate the regional air quality models used in developing emission strategies, and to track trends in air pollution abatement control measures' impact on improving air quality. In monitoring locations near major air pollution sources, source-oriented monitoring data can provide insight into how well industrial sources are controlling their pollutant emissions.
(c) Support for air pollution research studies. Air pollution data from the NCore network can be used to supplement data collected by researchers working on health effects assessments and atmospheric processes, or for monitoring methods development work.
1.1.1 In order to support the air quality management work indicated in the three basic air monitoring objectives, a network must be designed with a variety of types of monitoring sites. Monitoring sites must be capable of informing managers about many things including the peak air pollution levels, typical levels in populated areas, air pollution transported into and outside of a city or region, and air pollution levels near specific sources. To summarize some of these sites, here is a listing of six general site types:
(a) Sites located to determine the highest concentrations expected to occur in the area covered by the network.
(b) Sites located to measure typical concentrations in areas of high population density.
(c) Sites located to determine the impact of significant sources or source categories on air quality.
(d) Sites located to determine general background concentration levels.
(e) Sites located to determine the extent of regional pollutant transport among populated areas; and in support of secondary standards.
(f) Sites located to measure air pollution impacts on visibility, vegetation damage, or other welfare-based impacts.
1.1.2 This appendix contains criteria for the basic air monitoring requirements. The total number of monitoring sites that will serve the variety of data needs will be substantially higher than these minimum requirements provide. The optimum size of a particular network involves trade-offs among data needs and available resources. This regulation intends to provide for national air monitoring needs, and to lend support for the flexibility necessary to meet data collection needs of area air quality managers. The EPA, State, and local agencies will periodically collaborate on network design issues through the network assessment process outlined in Sec. 58.10.
1.1.3 This appendix focuses on the relationship between monitoring objectives, site types, and the geographic location of monitoring sites. Included are a rationale and set of general criteria for identifying candidate site locations in terms of physical characteristics which most closely match a specific monitoring objective. The criteria for more specifically locating the monitoring site, including spacing from roadways and vertical and horizontal probe and path placement, are described in appendix E to this part.
(a) To clarify the nature of the link between general monitoring objectives, site types, and the physical location of a particular monitor, the concept of spatial scale of representativeness is defined. The goal in locating monitors is to correctly match the spatial scale represented by the sample of monitored air with the spatial scale most appropriate for the monitoring site type, air pollutant to be measured, and the monitoring objective.
(b) Thus, spatial scale of representativeness is described in terms of the physical dimensions of the air parcel nearest to a monitoring site throughout which actual pollutant concentrations are reasonably similar. The scales of representativeness of most interest for the monitoring site types described above are as follows:
(1) Microscale--Defines the concentrations in air volumes associated with area dimensions ranging from several meters up to about 100 meters.
(2) Middle scale--Defines the concentration typical of areas up to several city blocks in size with dimensions ranging from about 100 meters to 0.5 kilometer.
(3) Neighborhood scale--Defines concentrations within some extended area of the city that has relatively uniform land use with dimensions in the 0.5 to 4.0 kilometers range. The neighborhood and urban scales listed below have the potential to overlap in applications that concern secondarily formed or homogeneously distributed air pollutants.
(4) Urban scale--Defines concentrations within an area of city-like dimensions, on the order of 4 to 50 kilometers. Within a city, the geographic placement of sources may result in there being no single site that can be said to represent air quality on an urban scale.
(5) Regional scale--Defines usually a rural area of reasonably homogeneous geography without large sources, and extends from tens to hundreds of kilometers.
(6) National and global scales--These measurement scales represent concentrations characterizing the nation and the globe as a whole.
(c) Proper siting of a monitor requires specification of the monitoring objective, the types of sites necessary to meet the objective, and then the desired spatial scale of representativeness. For example, consider the case where the objective is to determine NAAQS compliance by understanding the maximum ozone concentrations for an area. Such areas would most likely be located downwind of a metropolitan area, quite likely in a suburban residential area where children and other susceptible individuals are likely to be outdoors. Sites located in these areas are most likely to represent an urban scale of measurement. In this example, physical location was determined by considering ozone precursor emission patterns, public activity, and meteorological characteristics affecting ozone formation and dispersion. Thus, spatial scale of representativeness was not used in the selection process but was a result of site location.
(d) In some cases, the physical location of a site is determined from joint consideration of both the basic monitoring objective and the type of monitoring site desired, or required by this appendix. For example, to determine PM 2.5 concentrations which are typical over a geographic area having relatively high PM 2.5 concentrations, a neighborhood scale site is more appropriate. Such a site would likely be located in a residential or commercial area having a high overall PM 2.5 emission density but not in the immediate vicinity of any single dominant source. Note that in this example, the desired scale of representativeness was an important factor in determining the physical location of the monitoring site.
(e) In either case, classification of the monitor by its type and spatial scale of representativeness is necessary and will aid in interpretation of the monitoring data for a particular monitoring objective (e.g., public reporting, NAAQS compliance, or research support).
(f) Table D-1 of this appendix illustrates the relationship between the various site types that can be used to support the three basic monitoring objectives, and the scales of representativeness that are generally most appropriate for that type of site.
Table D-1 of Appendix D to Part 58--Relationship Between Site Types and
Scales of Representativeness------------------------------------------------------------------------
Site type Appropriate siting scales------------------------------------------------------------------------1. Highest concentration.................. Micro, middle, neighborhood
(sometimes urban or
regional for secondarily
formed pollutants).2. Population oriented.................... Neighborhood, urban.3. Source impact.......................... Micro, middle, neighborhood.4. General/background & regional transport Urban, regional.5. Welfare-related impacts................ Urban, regional.------------------------------------------------------------------------
2. General Monitoring Requirements
(a) The National ambient air monitoring system includes several types of monitoring stations, each targeting a key data collection need and each varying in technical sophistication.
(b) Research grade sites are platforms for scientific studies, either involved with health or welfare impacts, measurement methods development, or other atmospheric studies. These sites may be collaborative efforts between regulatory agencies and researchers with specific scientific objectives for each. Data from these sites might be collected with both traditional and experimental techniques, and data collection might involve specific laboratory analyses not common in routine measurement programs. The research grade sites are not required by regulation; however, they are included here due to their important role in supporting the air quality management program.
(c) The NCore multipollutant sites are sites that measure multiple pollutants in order to provide support to integrated air quality management data needs. NCore sites include both neighborhood and urban scale measurements in general, in a selection of metropolitan areas and a limited number of more rural locations. Continuous monitoring methods are to be used at the NCore sites when available for a pollutant to be measured, as it is important to have data collected over common time periods for integrated analyses. NCore multipollutant sites are intended to be long-term sites useful for a variety of applications including air quality trends analyses, model evaluation, and tracking metropolitan area statistics. As such, the NCore sites should be placed away from direct emission sources that could substantially impact the ability to detect area-wide concentrations. The Administrator must approve the NCore sites.
(d) Monitoring sites designated as SLAMS sites, but not as NCore sites, are intended to address specific air quality management interests, and as such, are frequently single-pollutant measurement sites. The EPA Regional Administrator must approve the SLAMS sites.
(e) This appendix uses the statistical-based definitions for metropolitan areas provided by the Office of Management and Budget and the Census Bureau. These areas are referred to as metropolitan statistical areas (MSA), micropolitan statistical areas, core-based statistical areas (CBSA), and combined statistical areas (CSA). A CBSA associated with at least one urbanized area of 50,000 population or greater is termed a Metropolitan Statistical Area (MSA). A CBSA associated with at least one urbanized cluster of at least 10,000 population or greater is termed a Micropolitan Statistical Area. CSA consist of two or more adjacent CBSA. In this appendix, the term MSA is used to refer to a Metropolitan Statistical Area. By definition, both MSA and CSA have a high degree of integration; however, many such areas cross State or other political boundaries. MSA and CSA may also cross more than one air shed. The EPA recognizes that State or local agencies must consider MSA/CSA boundaries and their own political boundaries and geographical characteristics in designing their air monitoring networks. The EPA recognizes that there may be situations where the EPA Regional Administrator and the affected State or local agencies may need to augment or to divide the overall MSA/CSA monitoring responsibilities and requirements among these various agencies to achieve an effective network design. Full monitoring requirements apply separately to each affected State or local agency in the absence of an agreement between the affected agencies and the EPA Regional Administrator.
3. Design Criteria for NCore Sites
(a) Each State (i.e. the fifty States, District of Columbia, Puerto Rico, and the Virgin Islands) is required to operate at least one NCore site. States may delegate this requirement to a local agency. States with many MSAs often also have multiple air sheds with unique characteristics and, often, elevated air pollution. These States include, at a minimum, California, Florida, Illinois, Michigan, New York, North Carolina, Ohio, Pennsylvania, and Texas. These States are required to identify one to two additional NCore sites in order to account for their unique situations. These additional sites shall be located to avoid proximity to large emission sources. Any State or local agency can propose additional candidate NCore sites or modifications to these requirements for approval by the Administrator. The NCore locations should be leveraged with other multipollutant air monitoring sites including PAMS sites, National Air Toxics Trends Stations (NATTS) sites, CASTNET sites, and STN sites. Site leveraging includes using the same monitoring platform and equipment to meet the objectives of the variety of programs where possible and advantageous.
(b) The NCore sites must measure, at a minimum, PM 2.5 particle mass using continuous and integrated/filter-based samplers, speciated PM 2.5, PM 10-2.5 particle mass, speciated PM 10-2.5, O3, SO2, CO, NO/NOy, wind speed, wind direction, relative humidity, and ambient temperature. NCore sites in CBSA with a population of 500,000 people (as determined in the latest Census) or greater shall also measure Pb either as Pb-TSP or Pb-PM 10. The EPA Regional Administrator may approve an alternative location for the Pb measurement where the alternative location would be more appropriate for logistical reasons and the measurement would provide data on typical Pb concentrations in the CBSA.
(1) Although the measurement of NOy is required in support of a number of monitoring objectives, available commercial instruments may indicate little difference in their measurement of NOy compared to the conventional measurement of NOX, particularly in areas with relatively fresh sources of nitrogen emissions. Therefore, in areas with negligible expected difference between NOy and NOX measured concentrations, the Administrator may allow for waivers that permit NOX monitoring to be substituted for the required NOy monitoring at applicable NCore sites.
(2) EPA recognizes that, in some cases, the physical location of the NCore site may not be suitable for representative meteorological measurements due to the site's physical surroundings. It is also possible that nearby meteorological measurements may be able to fulfill this data need. In these cases, the requirement for meteorological monitoring can be waived by the Administrator.
(c) [Reserved]
(d) Siting criteria are provided for urban and rural locations. Sites with significant historical records that do not meet siting criteria may be approved as NCore by the Administrator. Sites with the suite of NCore measurements that are explicitly designed for other monitoring objectives are exempt from these siting criteria (e.g., a near-roadway site).
(1) Urban NCore stations are to be generally located at urban or neighborhood scale to provide representative concentrations of exposure expected throughout the metropolitan area; however, a middle-scale site may be acceptable in cases where the site can represent many such locations throughout a metropolitan area.
(2) Rural NCore stations are to be located to the maximum extent practicable at a regional or larger scale away from any large local emission source, so that they represent ambient concentrations over an extensive area.
4. Pollutant-Specific Design Criteria for SLAMS Sites
(a) State, and where appropriate, local agencies must operate O3 sites for various locations depending upon area size (in terms of population and geographic characteristics) and typical peak concentrations (expressed in percentages below, or near the O3 NAAQS). Specific SLAMS O3 site minimum requirements are included in Table D-2 of this appendix. The NCore sites are expected to complement the O3 data collection that takes place at single-pollutant SLAMS sites, and both types of sites can be used to meet the network minimum requirements. The total number of O3 sites needed to support the basic monitoring objectives of public data reporting, air quality mapping, compliance, and understanding O3-related atmospheric processes will include more sites than these minimum numbers required in Table D-2 of this appendix. The EPA Regional Administrator and the responsible State or local air monitoring agency must work together to design and/or maintain the most appropriate O3 network to service the variety of data needs in an area.
Table D-2 of Appendix D to Part 58-- SLAMS Minimum O3 Monitoring
Requirements------------------------------------------------------------------------
Most recent 3-year
design value Most recent 3-year
concentrations design value
MSA population \1 2\ "85% of any O3 concentrations
NAAQS \3\ <85% of any O3
NAAQS \3 4\------------------------------------------------------------------------>10 million..................... 4 24-10 million.................... 3 1350,000-<4 million.............. 2 1
50,000-<350,000 \5\............. 1 0------------------------------------------------------------------------\1\ Minimum monitoring requirements apply to the Metropolitan
statistical area (MSA).\2\ Population based on latest available census figures.\3\ The ozone (O3) National Ambient Air Quality Standards (NAAQS) levels
and forms are defined in 40 CFR part 50.\4\ These minimum monitoring requirements apply in the absence of a
design value.\5\ Metropolitan statistical areas (MSA) must contain an urbanized area
of 50,000 or more population.
(b) Within an O3 network, at least one O3 site for each MSA, or CSA if multiple MSAs are involved, must be designed to record the maximum concentration for that particular metropolitan area. More than one maximum concentration site may be necessary in some areas. Table D-2 of this appendix does not account for the full breadth of additional factors that would be considered in designing a complete O3 monitoring program for an area. Some of these additional factors include geographic size, population density, complexity of terrain and meteorology, adjacent O3 monitoring programs, air pollution transport from neighboring areas, and measured air quality in comparison to all forms of the O3 NAAQS (i.e., 8-hour and 1-hour forms). Networks must be designed to account for all of these area characteristics. Network designs must be re-examined in periodic network assessments. Deviations from the above O3 requirements are allowed if approved by the EPA Regional Administrator.
(c) The appropriate spatial scales for O3 sites are neighborhood, urban, and regional. Since O3 requires appreciable formation time, the mixing of reactants and products occurs over large volumes of air, and this reduces the importance of monitoring small scale spatial variability.
(1) Neighborhood scale--Measurements in this category represent conditions throughout some reasonably homogeneous urban sub-region, with dimensions of a few kilometers. Homogeneity refers to pollutant concentrations. Neighborhood scale data will provide valuable information for developing, testing, and revising concepts and models that describe urban/regional concentration patterns. These data will be useful to the understanding and definition of processes that take periods of hours to occur and hence involve considerable mixing and transport. Under stagnation conditions, a site located in the neighborhood scale may also experience peak concentration levels within a metropolitan area.
(2) Urban scale--Measurement in this scale will be used to estimate concentrations over large portions of an urban area with dimensions of several kilometers to 50 or more kilometers. Such measurements will be used for determining trends, and designing area-wide control strategies. The urban scale sites would also be used to measure high concentrations downwind of the area having the highest precursor emissions.
(3) Regional scale--This scale of measurement will be used to typify concentrations over large portions of a metropolitan area and even larger areas with dimensions of as much as hundreds of kilometers. Such measurements will be useful for assessing the O3 that is transported to and from a metropolitan area, as well as background concentrations. In some situations, particularly when considering very large metropolitan areas with complex source mixtures, regional scale sites can be the maximum concentration location.
(d) EPA's technical guidance documents on O3 monitoring network design should be used to evaluate the adequacy of each existing O3 monitor, to relocate an existing site, or to locate any new O3 sites.
(e) For locating a neighborhood scale site to measure typical city concentrations, a reasonably homogeneous geographical area near the center of the region should be selected which is also removed from the influence of major NOX sources. For an urban scale site to measure the high concentration areas, the emission inventories should be used to define the extent of the area of important nonmethane hydrocarbons and NOX emissions. The meteorological conditions that occur during periods of maximum photochemical activity should be determined. These periods can be identified by examining the meteorological conditions that occur on the highest O3 air quality days. Trajectory analyses, an evaluation of wind and emission patterns on high O3 days, can also be useful in evaluating an O3 monitoring network. In areas without any previous O3 air quality measurements, meteorological and O3 precursor emissions information would be useful.
(f) Once the meteorological and air quality data are reviewed, the prospective maximum concentration monitor site should be selected in a direction from the city that is most likely to observe the highest O3 concentrations, more specifically, downwind during periods of photochemical activity. In many cases, these maximum concentration O3 sites will be located 10 to 30 miles or more downwind from the urban area where maximum O3 precursor emissions originate. The downwind direction and appropriate distance should be determined from historical meteorological data collected on days which show the potential for producing high O3 levels. Monitoring agencies are to consult with their EPA Regional Office when considering siting a maximum O3 concentration site.
(g) In locating a neighborhood scale site which is to measure high concentrations, the same procedures used for the urban scale are followed except that the site should be located closer to the areas bordering on the center city or slightly further downwind in an area of high density population.
(h) For regional scale background monitoring sites, similar meteorological analysis as for the maximum concentration sites may also inform the decisions for locating regional scale sites. Regional scale sites may be located to provide data on O3 transport between cities, as background sites, or for other data collection purposes. Consideration of both area characteristics, such as meteorology, and the data collection objectives, such as transport, must be jointly considered for a regional scale site to be useful.
(i) Since O3 levels decrease significantly in the colder parts of the year in many areas, O3 is required to be monitored at SLAMS monitoring sites only during the ``ozone season'' as designated in the AQS files on a State-by-State basis and described below in Table D-3 of this appendix. Deviations from the O3 monitoring season must be approved by the EPA Regional Administrator, documented within the annual monitoring network plan, and updated in AQS. Information on how to analyze O3 data to support a change to the O3 season in support of the 8-hour standard for a specific State can be found in reference 8 to this appendix.
Table D-3 of Appendix D to Part 58--Ozone Monitoring Season by State------------------------------------------------------------------------
State Begin month End month------------------------------------------------------------------------Alabama......................... March............. OctoberAlaska.......................... April............. OctoberArizona......................... January........... DecemberArkansas........................ March............. NovemberCalifornia...................... January........... DecemberColorado........................ March............. SeptemberConnecticut..................... April............. SeptemberDelaware........................ April............. OctoberDistrict of Columbia............ April............. OctoberFlorida......................... March............. OctoberGeorgia......................... March............. OctoberHawaii.......................... January........... DecemberIdaho........................... May............... SeptemberIllinois........................ April............. OctoberIndiana......................... April............. SeptemberIowa............................ April............. OctoberKansas.......................... April............. OctoberKentucky........................ March............. OctoberLouisiana AQCR 019,022.......... March............. OctoberLouisiana AQCR 106.............. January........... DecemberMaine........................... April............. SeptemberMaryland........................ April............. OctoberMassachusetts................... April............. SeptemberMichigan........................ April............. SeptemberMinnesota....................... April............. OctoberMississippi..................... March............. OctoberMissouri........................ April............. OctoberMontana......................... June.............. SeptemberNebraska........................ April............. OctoberNevada.......................... January........... DecemberNew Hampshire................... April............. SeptemberNew Jersey...................... April............. OctoberNew Mexico...................... January........... DecemberNew York........................ April............. OctoberNorth Carolina.................. April............. OctoberNorth Dakota.................... May............... SeptemberOhio............................ April............. OctoberOklahoma........................ March............. NovemberOregon.......................... May............... SeptemberPennsylvania.................... April............. OctoberPuerto Rico..................... January........... DecemberRhode Island.................... April............. SeptemberSouth Carolina.................. April............. OctoberSouth Dakota.................... June.............. SeptemberTennessee....................... March............. OctoberTexas AQCR 106,153, 213, 214, January........... December
216.Texas AQCR 022, 210, 211, 212, March............. October
215, 217, 218.Utah............................ May............... SeptemberVermont......................... April............. SeptemberVirginia........................ April............. OctoberWashington...................... May............... SeptemberWest Virginia................... April............. OctoberWisconsin....................... April 15.......... October 15Wyoming......................... April............. OctoberAmerican Samoa.................. January........... DecemberGuam............................ January........... DecemberVirgin Islands.................. January........... December------------------------------------------------------------------------
4.2 Carbon Monoxide (CO) Design Criteria
(a) Except as provided in subsection (b), one CO monitor is required to operate collocated with one required near-road NO2 monitor, as required in Section 4.3.2 of this part, in CBSAs having a population of 1,000,000 or more persons. If a CBSA has more than one required near-road NO2 monitor, only one CO monitor is required to be collocated with a near-road NO2 monitor within that CBSA.
(b) If a state provides quantitative evidence demonstrating that peak ambient CO concentrations would occur in a near-road location which meets microscale siting criteria in Appendix E of this part but is not a near-road NO2 monitoring site, then the EPA Regional Administrator may approve a request by a state to use such an alternate near-road location for a CO monitor in place of collocating a monitor at near-road NO2 monitoring site.
(a) The Regional Administrators, in collaboration with states, may require additional CO monitors above the minimum number of monitors required in 4.2.1 of this part, where the minimum monitoring requirements are not sufficient to meet monitoring objectives. The Regional Administrator may require, at his/her discretion, additional monitors in situations where data or other information suggest that CO concentrations may be approaching or exceeding the NAAQS. Such situations include, but are not limited to, (1) characterizing impacts on ground-level concentrations due to stationary CO sources, (2) characterizing CO concentrations in downtown areas or urban street canyons, and (3) characterizing CO concentrations in areas that are subject to high ground level CO concentrations particularly due to or enhanced by topographical and meteorological impacts. The Regional Administrator and the responsible State or local air monitoring agency shall work together to design and maintain the most appropriate CO network to address the data needs for an area, and include all monitors under this provision in the annual monitoring network plan.
(1) characterizing impacts on ground-level concentrations due to stationary CO sources, (2) characterizing CO concentrations in downtown areas or urban street canyons, and (3) characterizing CO concentrations in areas that are subject to high ground level CO concentrations particularly due to or enhanced by topographical and meteorological impacts. The Regional Administrator and the responsible State or local air monitoring agency shall work together to design and maintain the most appropriate CO network to address the data needs for an area, and include all monitors under this provision in the annual monitoring network plan.
(a) Microscale and middle scale measurements are the most useful site classifications for CO monitoring sites since most people have the potential for exposure on these scales. Carbon monoxide maxima occur primarily in areas near major roadways and intersections with high traffic density and often in areas with poor atmospheric ventilation.
(1) Microscale--Microscale measurements typically represent areas in close proximity to major roadways, within street canyons, over sidewalks, and in some cases, point and area sources. Emissions on roadways result in high ground level CO concentrations at the microscale, where concentration gradients generally exhibit a marked decrease with increasing downwind distance from major roads, or within downtown areas including urban street canyons. Emissions from stationary point and area sources, and non-road sources may, under certain plume conditions, result in high ground level concentrations at the microscale.
(2) Middle scale--Middle scale measurements are intended to represent areas with dimensions from 100 meters to 0.5 kilometer. In certain cases, middle scale measurements may apply to areas that have a total length of several kilometers, such as ``line'' emission source areas. This type of emission sources areas would include air quality along a commercially developed street or shopping plaza, freeway corridors, parking lots and feeder streets.
(3) Neighborhood scale--Neighborhood scale measurements are intended to represent areas with dimensions from 0.5 kilometers to 4 kilometers. Measurements of CO in this category would represent conditions throughout some reasonably urban sub-regions. In some cases, neighborhood scale data may represent not only the immediate neighborhood spatial area, but also other similar such areas across the larger urban area. Neighborhood scale measurements provide relative area-wide concentration data which are useful for providing relative urban background concentrations, supporting health and scientific research, and for use in modeling.
4.3 Nitrogen Dioxide (NO2) Design Criteria
4.3.1 General Requirements
(a) State and, where appropriate, local agencies must operate a minimum number of required NO2 monitoring sites as described below.
4.3.2 Requirement for Near-road NO2 Monitors
(a) Within the NO2 network, there must be one microscale near-road NO2 monitoring station in each CBSA with a population of 500,000 or more persons to monitor a location of expected maximum hourly concentrations sited near a major road with high AADT counts as specified in paragraph 4.3.2(a)(1) of this appendix. An additional near-road NO2 monitoring station is required for any CBSA with a population of 2,500,000 persons or more, or in any CBSA with a population of 500,000 or more persons that has one or more roadway segments with 250,000 or greater AADT counts to monitor a second location of expected maximum hourly concentrations. CBSA populations shall be based on the latest available census figures.
(1) The near-road NO2 monitoring stations shall be selected by ranking all road segments within a CBSA by AADT and then identifying a location or locations adjacent to those highest ranked road segments, considering fleet mix, roadway design, congestion patterns, terrain, and meteorology, where maximum hourly NO2 concentrations are expected to occur and siting criteria can be met in accordance with appendix E of this part. Where a State or local air monitoring agency identifies multiple acceptable candidate sites where maximum hourly NO2 concentrations are expected to occur, the monitoring agency shall consider the potential for population exposure in the criteria utilized to select the final site location. Where one CBSA is required to have two near-road NO2 monitoring stations, the sites shall be differentiated from each other by one or more of the following factors: fleet mix; congestion patterns; terrain; geographic area within the CBSA; or different route, interstate, or freeway designation.
(b) Measurements at required near-road NO2 monitor sites utilizing chemiluminescence FRMs must include at a minimum: NO, NO2, and NOX.
4.3.3 Requirement for Area-wide NO2 Monitoring
(a) Within the NO2 network, there must be one monitoring station in each CBSA with a population of 1,000,000 or more persons to monitor a location of expected highest NO2 concentrations representing the neighborhood or larger spatial scales. PAMS sites collecting NO2 data that are situated in an area of expected high NO2 concentrations at the neighborhood or larger spatial scale may be used to satisfy this minimum monitoring requirement when the NO2 monitor is operated year round. Emission inventories and meteorological analysis should be used to identify the appropriate locations within a CBSA for locating required area-wide NO2 monitoring stations. CBSA populations shall be based on the latest available census figures.
4.3.4 Regional Administrator Required Monitoring
(a) The Regional Administrators, in collaboration with States, must require a minimum of forty additional NO2 monitoring stations nationwide in any area, inside or outside of CBSAs, above the minimum monitoring requirements, with a primary focus on siting these monitors in locations to protect susceptible and vulnerable populations. The Regional Administrators, working with States, may also consider additional factors described in paragraph (b) below to require monitors beyond the minimum network requirement.
(b) The Regional Administrators may require monitors to be sited inside or outside of CBSAs in which:
(i) The required near-road monitors do not represent all locations of expected maximum hourly NO2 concentrations in an area and NO2 concentrations may be approaching or exceeding the NAAQS in that area;
(ii) Areas that are not required to have a monitor in accordance with the monitoring requirements and NO2 concentrations may be approaching or exceeding the NAAQS; or
(iii) The minimum monitoring requirements for area-wide monitors are not sufficient to meet monitoring objectives.
(c) The Regional Administrator and the responsible State or local air monitoring agency should work together to design and/or maintain the most appropriate NO2 network to address the data needs for an area, and include all monitors under this provision in the annual monitoring network plan.
4.3.5 NO2 Monitoring Spatial Scales
(a) The most important spatial scale for near-road NO2 monitoring stations to effectively characterize the maximum expected hourly NO2 concentration due to mobile source emissions on major roadways is the microscale. The most important spatial scales for other monitoring stations characterizing maximum expected hourly NO2 concentrations are the microscale and middle scale. The most important spatial scale for area-wide monitoring of high NO2 concentrations is the neighborhood scale.
(1) Microscale--This scale represents areas in close proximity to major roadways or point and area sources. Emissions from roadways result in high ground level NO2 concentrations at the microscale, where concentration gradients generally exhibit a marked decrease with increasing downwind distance from major roads. As noted in appendix E of this part, near-road NO2 monitoring stations are required to be within 50 meters of target road segments in order to measure expected peak concentrations. Emissions from stationary point and area sources, and non-road sources may, under certain plume conditions, result in high ground level concentrations at the microscale. The microscale typically represents an area impacted by the plume with dimensions extending up to approximately 100 meters.
(2) Middle scale--This scale generally represents air quality levels in areas up to several city blocks in size with dimensions on the order of approximately 100 meters to 500 meters. The middle scale may include locations of expected maximum hourly concentrations due to proximity to major NO2 point, area, and/or non-road sources.
(3) Neighborhood scale--The neighborhood scale represents air quality conditions throughout some relatively uniform land use areas with dimensions in the 0.5 to 4.0 kilometer range. Emissions from stationary point and area sources may, under certain plume conditions, result in high NO2 concentrations at the neighborhood scale. Where a neighborhood site is located away from immediate NO2 sources, the site may be useful in representing typical air quality values for a larger residential area, and therefore suitable for population exposure and trends analyses.
(4) Urban scale--Measurements in this scale would be used to estimate concentrations over large portions of an urban area with dimensions from 4 to 50 kilometers. Such measurements would be useful for assessing trends in area-wide air quality, and hence, the effectiveness of large scale air pollution control strategies. Urban scale sites may also support other monitoring objectives of the NO2 monitoring network identified in paragraph 4.3.4 above.
4.3.6 NOy Monitoring
(a) NO/NOy measurements are included within the NCore multi-pollutant site requirements and the PAMS program. These NO/NOy measurements will produce conservative estimates for NO2 that can be used to ensure tracking continued compliance with the NO2 NAAQS. NO/NOy monitors are used at these sites because it is important to collect data on total reactive nitrogen species for understanding O3 photochemistry.
4.4 Sulfur Dioxide (SO2) Design Criteria.
(a) State and, where appropriate, local agencies must operate a minimum number of required SO2 monitoring sites as described below.
(a) The population weighted emissions index (PWEI) shall be calculated by States for each core based statistical area (CBSA) they contain or share with another State or States for use in the implementation of or adjustment to the SO2 monitoring network. The PWEI shall be calculated by multiplying the population of each CBSA, using the most current census data or estimates, and the total amount of SO2 in tons per year emitted within the CBSA area, using an aggregate of the most recent county level emissions data available in the National Emissions Inventory for each county in each CBSA. The resulting product shall be divided by one million, providing a PWEI value, the units of which are million persons-tons per year. For any CBSA with a calculated PWEI value equal to or greater than 1,000,000, a minimum of three SO2 monitors are required within that CBSA. For any CBSA with a calculated PWEI value equal to or greater than 100,000, but less than 1,000,000, a minimum of two SO2 monitors are required within that CBSA. For any CBSA with a calculated PWEI value equal to or greater than 5,000, but less than 100,000, a minimum of one SO2 monitor is required within that CBSA.
(1) The SO2 monitoring site(s) required as a result of the calculated PWEI in each CBSA shall satisfy minimum monitoring requirements if the monitor is sited within the boundaries of the parent CBSA and is one of the following site types (as defined in section 1.1.1 of this appendix): population exposure, highest concentration, source impacts, general background, or regional transport. SO2 monitors at NCore stations may satisfy minimum monitoring requirements if that monitor is located within a CBSA with minimally required monitors under this part. Any monitor that is sited outside of a CBSA with minimum monitoring requirements to assess the highest concentration resulting from the impact of significant sources or source categories existing within that CBSA shall be allowed to count towards minimum monitoring requirements for that CBSA.
(a) The Regional Administrator may require additional SO2 monitoring stations above the minimum number of monitors required in 4.4.2 of this part, where the minimum monitoring requirements are not sufficient to meet monitoring objectives. The Regional Administrator may require, at his/her discretion, additional monitors in situations where an area has the potential to have concentrations that may violate or contribute to the violation of the NAAQS, in areas impacted by sources which are not conducive to modeling, or in locations with susceptible and vulnerable populations, which are not monitored under the minimum monitoring provisions described above. The Regional Administrator and the responsible State or local air monitoring agency shall work together to design and/or maintain the most appropriate SO2 network to provide sufficient data to meet monitoring objectives.
(a) The appropriate spatial scales for SO2 SLAMS monitors are the microscale, middle, neighborhood, and urban scales. Monitors sited at the microscale, middle, and neighborhood scales are suitable for determining maximum hourly concentrations for SO2. Monitors sited at urban scales are useful for identifying SO2 transport, trends, and, if sited upwind of local sources, background concentrations.
(1) Microscale--This scale would typify areas in close proximity to SO2 point and area sources. Emissions from stationary point and area sources, and non-road sources may, under certain plume conditions, result in high ground level concentrations at the microscale. The microscale typically represents an area impacted by the plume with dimensions extending up to approximately 100 meters.
(2) Middle scale--This scale generally represents air quality levels in areas up to several city blocks in size with dimensions on the order of approximately 100 meters to 500 meters. The middle scale may include locations of expected maximum short-term concentrations due to proximity to major SO2 point, area, and/or non-road sources.
(3) Neighborhood scale--The neighborhood scale would characterize air quality conditions throughout some relatively uniform land use areas with dimensions in the 0.5 to 4.0 kilometer range. Emissions from stationary point and area sources may, under certain plume conditions, result in high SO2 concentrations at the neighborhood scale. Where a neighborhood site is located away from immediate SO2 sources, the site may be useful in representing typical air quality values for a larger residential area, and therefore suitable for population exposure and trends analyses.
(4) Urban scale--Measurements in this scale would be used to estimate concentrations over large portions of an urban area with dimensions from 4 to 50 kilometers. Such measurements would be useful for assessing trends in area-wide air quality, and hence, the effectiveness of large scale air pollution control strategies. Urban scale sites may also support other monitoring objectives of the SO2 monitoring network such as identifying trends, and when monitors are sited upwind of local sources, background concentrations.
(a) SO2 measurements are included within the NCore multipollutant site requirements as described in paragraph (3)(b) of this appendix. NCore-based SO2 measurements are primarily used to characterize SO2 trends and assist in understanding SO2 transport across representative areas in urban or rural locations and are also used for comparison with the SO2 NAAQS. SO2 monitors at NCore sites that exist in CBSAs with minimum monitoring requirements per section 4.4.2 above shall be allowed to count towards those minimum monitoring requirements.
(a) State and, where appropriate, local agencies are required to conduct ambient air Pb monitoring near Pb sources which are expected to or have been shown to contribute to a maximum Pb concentration in ambient air in excess of the NAAQS, taking into account the logistics and potential for population exposure. At a minimum, there must be one source-oriented SLAMS site located to measure the maximum Pb concentration in ambient air resulting from each non-airport Pb source which emits 0.50 or more tons per year and from each airport which emits 1.0 or more tons per year based on either the most recent National Emission Inventory (http://www.epa.gov/ttn/chief/eiinformation.html) or other scientifically justifiable methods and data (such as improved emissions factors or site-specific data) taking into account logistics and the potential for population exposure.
(i) One monitor may be used to meet the requirement in paragraph 4.5(a) for all sources involved when the location of the maximum Pb concentration due to one Pb source is expected to also be impacted by Pb emissions from a nearby source (or multiple sources). This monitor must be sited, taking into account logistics and the potential for population exposure, where the Pb concentration from all sources combined is expected to be at its maximum.
(ii) The Regional Administrator may waive the requirement in paragraph 4.5(a) for monitoring near Pb sources if the State or, where appropriate, local agency can demonstrate the Pb source will not contribute to a maximum Pb concentration in ambient air in excess of 50 percent of the NAAQS (based on historical monitoring data, modeling, or other means). The waiver must be renewed once every 5 years as part of the network assessment required under Sec. 58.10(d).
(iii) State and, where appropriate, local agencies are required to conduct ambient air Pb monitoring near each of the airports listed in Table D-3A for a period of 12 consecutive months commencing no later than December 27, 2011. Monitors shall be sited to measure the maximum Pb concentration in ambient air, taking into account logistics and the potential for population exposure, and shall use an approved Pb-TSP Federal Reference Method or Federal Equivalent Method. Any monitor that exceeds 50 percent of the Pb NAAQS on a rolling 3-month average (as determined according to 40 CFR part 50, Appendix R) shall become a required monitor under paragraph 4.5(c) of this Appendix, and shall continue to monitor for Pb unless a waiver is granted allowing it to stop operating as allowed by the provisions in paragraph 4.5(a)(ii) of this appendix. Data collected shall be submitted to the Air Quality System database according to the requirements of 40 CFR part 58.16.
Table D-3A Airports To Be Monitored for Lead------------------------------------------------------------------------
Airport County State------------------------------------------------------------------------Merrill Field...................... Anchorage............. AKPryor Field Regional............... Limestone............. ALPalo Alto Airport of Santa Clara Santa Clara........... CA
County.McClellan-Palomar.................. San Diego............. CAReid-Hillview...................... Santa Clara........... CAGillespie Field.................... San Diego............. CASan Carlos......................... San Mateo............. CANantucket Memorial................. Nantucket............. MAOakland County International....... Oakland............... MIRepublic........................... Suffolk............... NYBrookhaven......................... Suffolk............... NYStinson Municipal.................. Bexar................. TXNorthwest Regional................. Denton................ TXHarvey Field....................... Snohomish............. WAAuburn Municipal................... King.................. WA------------------------------------------------------------------------
(b) State and, where appropriate, local agencies are required to conduct non-source-oriented Pb monitoring at each NCore site required under paragraph 3 of this appendix in a CBSA with a population of 500,000 or more.
(c) The EPA Regional Administrator may require additional monitoring beyond the minimum monitoring requirements contained in paragraphs 4.5(a) and 4.5(b) where the likelihood of Pb air quality violations is significant or where the emissions density, topography, or population locations are complex and varied. EPA Regional Administrators may require additional monitoring at locations including, but not limited to, those near existing additional industrial sources of Pb, recently closed industrial sources of Pb, airports where piston-engine aircraft emit Pb, and other sources of re-entrained Pb dust.
(d) The most important spatial scales for source-oriented sites to effectively characterize the emissions from point sources are microscale and middle scale. The most important spatial scale for non-source-oriented sites to characterize typical lead concentrations in urban areas is the neighborhood scale. Monitor siting should be conducted in accordance with 4.5(a)(i) with respect to source-oriented sites.
(1) Microscale--This scale would typify areas in close proximity to lead point sources. Emissions from point sources such as primary and secondary lead smelters, and primary copper smelters may under fumigation conditions likewise result in high ground level concentrations at the microscale. In the latter case, the microscale would represent an area impacted by the plume with dimensions extending up to approximately 100 meters. Pb monitors in areas where the public has access, and particularly children have access, are desirable because of the higher sensitivity of children to exposures of elevated Pb concentrations.
(2) Middle scale--This scale generally represents Pb air quality levels in areas up to several city blocks in size with dimensions on the order of approximately 100 meters to 500 meters. The middle scale may for example, include schools and playgrounds in center city areas which are close to major Pb point sources. Pb monitors in such areas are desirable because of the higher sensitivity of children to exposures of elevated Pb concentrations (reference 3 of this appendix). Emissions from point sources frequently impact on areas at which single sites may be located to measure concentrations representing middle spatial scales.
(3) Neighborhood scale--The neighborhood scale would characterize air quality conditions throughout some relatively uniform land use areas with dimensions in the 0.5 to 4.0 kilometer range. Sites of this scale would provide monitoring data in areas representing conditions where children live and play. Monitoring in such areas is important since this segment of the population is more susceptible to the effects of Pb. Where a neighborhood site is located away from immediate Pb sources, the site may be very useful in representing typical air quality values for a larger residential area, and therefore suitable for population exposure and trends analyses.
(d) Technical guidance is found in references 4 and 5 of this appendix. These documents provide additional guidance on locating sites to meet specific urban area monitoring objectives and should be used in locating new sites or evaluating the adequacy of existing sites.
4.6 Particulate Matter (PM 10) Design Criteria.4(a) Table D-4 indicates the approximate number of permanent stations required in MSAs to characterize national and regional PM 10 air quality trends and geographical patterns. The number of PM 10 stations in areas where MSA populations exceed 1,000,000 must be in the range from 2 to 10 stations, while in low population urban areas, no more than two stations are required. A range of monitoring stations is specified in Table D-4 because sources of pollutants and local control efforts can vary from one part of the country to another and therefore, some flexibility is allowed in selecting the actual number of stations in any one locale. Modifications from these PM 10 monitoring requirements must be approved by the Regional Administrator.
Table D-4 of Appendix D to Part 58--PM 10 Minimum Monitoring Requirements (Approximate Number of Stations Per
MSA) \1\----------------------------------------------------------------------------------------------------------------
Low concentration
Population category High concentration Medium \4 5\
\2\ concentration \3\---------------------------------------------------------------------------------------------------------------->1,000,000.......................................... 6-10 4-8 2-4500,000-1,000,000................................... 4-8 2-4 1-2250,000-500,000..................................... 3-4 1-2 0-1100,000-250,000..................................... 1-2 0-1 0----------------------------------------------------------------------------------------------------------------\1\ Selection of urban areas and actual numbers of stations per area will be jointly determined by EPA and the
State agency.\2\ High concentration areas are those for which ambient PM10 data show ambient concentrations exceeding the PM
10 NAAQS by 20 percent or more.\3\ Medium concentration areas are those for which ambient PM10 data show ambient concentrations exceeding 80
percent of the PM 10 NAAQS.\4\ Low concentration areas are those for which ambient PM10 data show ambient concentrations less than 80
percent of the PM 10 NAAQS.\5\ These minimum monitoring requirements apply in the absence of a design value.
(b) Although microscale monitoring may be appropriate in some circumstances, the most important spatial scales to effectively characterize the emissions of PM 10 from both mobile and stationary sources are the middle scales and neighborhood scales.
(1) Microscale--This scale would typify areas such as downtown street canyons, traffic corridors, and fence line stationary source monitoring locations where the general public could be exposed to maximum PM 10 concentrations. Microscale particulate matter sites should be located near inhabited buildings or locations where the general public can be expected to be exposed to the concentration measured. Emissions from stationary sources such as primary and secondary smelters, power plants, and other large industrial processes may, under certain plume conditions, likewise result in high ground level concentrations at the microscale. In the latter case, the microscale would represent an area impacted by the plume with dimensions extending up to approximately 100 meters. Data collected at microscale sites provide information for evaluating and developing hot spot control measures.
(2) Middle scale--Much of the short-term public exposure to coarse fraction particles (PM 10) is on this scale and on the neighborhood scale. People moving through downtown areas or living near major roadways or stationary sources, may encounter particulate pollution that would be adequately characterized by measurements of this spatial scale. Middle scale PM 10 measurements can be appropriate for the evaluation of possible short-term exposure public health effects. In many situations, monitoring sites that are representative of micro-scale or middle-scale impacts are not unique and are representative of many similar situations. This can occur along traffic corridors or other locations in a residential district. In this case, one location is representative of a neighborhood of small scale sites and is appropriate for evaluation of long-term or chronic effects. This scale also includes the characteristic concentrations for other areas with dimensions of a few hundred meters such as the parking lot and feeder streets associated with shopping centers, stadia, and office buildings. In the case of PM 10, unpaved or seldomly swept parking lots associated with these sources could be an important source in addition to the vehicular emissions themselves.
(3) Neighborhood scale--Measurements in this category represent conditions throughout some reasonably homogeneous urban sub-region with dimensions of a few kilometers and of generally more regular shape than the middle scale. Homogeneity refers to the particulate matter concentrations, as well as the land use and land surface characteristics. In some cases, a location carefully chosen to provide neighborhood scale data would represent not only the immediate neighborhood but also neighborhoods of the same type in other parts of the city. Neighborhood scale PM 10 sites provide information about trends and compliance with standards because they often represent conditions in areas where people commonly live and work for extended periods. Neighborhood scale data could provide valuable information for developing, testing, and revising models that describe the larger-scale concentration patterns, especially those models relying on spatially smoothed emission fields for inputs. The neighborhood scale measurements could also be used for neighborhood comparisons within or between cities.
4.7 Fine Particulate Matter (PM 2.5) Design Criteria.
(a) State, and where applicable local, agencies must operate the minimum number of required PM 2.5 SLAMS sites listed in Table D-5 of this appendix. The NCore sites are expected to complement the PM 2.5 data collection that takes place at non-NCore SLAMS sites, and both types of sites can be used to meet the minimum PM 2.5 network requirements. Deviations from these PM 2.5 monitoring requirements must be approved by the EPA Regional Administrator.
Table D-5 of Appendix D to Part 58--PM 2.5 Minimum Monitoring
Requirements------------------------------------------------------------------------
Most recent 3-year
design value "85% Most recent 3-year
MSA population \1 2\ of any PM 2.5 design value <85%
NAAQS \3\ of any PM 2.5
NAAQS \3 4\------------------------------------------------------------------------>1,000,000...................... 3 2500,000-1,000,000............... 2 150,000-<500,000 \5\............. 1 0------------------------------------------------------------------------\1\ Minimum monitoring requirements apply to the Metropolitan
statistical area (MSA).\2\ Population based on latest available census figures.\3\ The PM 2.5 National Ambient Air Quality Standards (NAAQS) levels and
forms are defined in 40 CFR part 50.\4\ These minimum monitoring requirements apply in the absence of a
design value.\5\ Metropolitan statistical areas (MSA) must contain an urbanized area
of 50,000 or more population.
(b) Specific Design Criteria for PM 2.5. The required monitoring stations or sites must be sited to represent area-wide air quality. These sites can include sites collocated at PAMS. These monitoring stations will typically be at neighborhood or urban-scale; however, micro-or middle-scale PM 2.5 monitoring sites that represent many such locations throughout a metropolitan area are considered to represent area-wide air quality.
(1) At least one monitoring station is to be sited at neighborhood or larger scale in an area of expected maximum concentration.
(2) For CBSAs with a population of 1,000,000 or more persons, at least one PM 2.5 monitor is to be collocated at a near-road NO2 station required in section 4.3.2(a) of this appendix.
(3) For areas with additional required SLAMS, a monitoring station is to be sited in an area of poor air quality.
(4) Additional technical guidance for siting PM 2.5 monitors is provided in references 6 and 7 of this appendix.
(c) The most important spatial scale to effectively characterize the emissions of particulate matter from both mobile and stationary sources is the neighborhood scale for PM 2.5. For purposes of establishing monitoring sites to represent large homogenous areas other than the above scales of representativeness and to characterize regional transport, urban or regional scale sites would also be needed. Most PM 2.5 monitoring in urban areas should be representative of a neighborhood scale.
(1) Micro-scale. This scale would typify areas such as downtown street canyons and traffic corridors where the general public would be exposed to maximum concentrations from mobile sources. In some circumstances, the micro-scale is appropriate for particulate sites. SLAMS sites measured at the micro-scale level should, however, be limited to urban sites that are representative of long-term human exposure and of many such microenvironments in the area. In general, micro-scale particulate matter sites should be located near inhabited buildings or locations where the general public can be expected to be exposed to the concentration measured. Emissions from stationary sources such as primary and secondary smelters, power plants, and other large industrial processes may, under certain plume conditions, likewise result in high ground level concentrations at the micro-scale. In the latter case, the micro-scale would represent an area impacted by the plume with dimensions extending up to approximately 100 meters. Data collected at micro-scale sites provide information for evaluating and developing hot spot control measures.
(2) Middle scale--People moving through downtown areas, or living near major roadways, encounter particle concentrations that would be adequately characterized by this spatial scale. Thus, measurements of this type would be appropriate for the evaluation of possible short-term exposure public health effects of particulate matter pollution. In many situations, monitoring sites that are representative of microscale or middle-scale impacts are not unique and are representative of many similar situations. This can occur along traffic corridors or other locations in a residential district. In this case, one location is representative of a number of small scale sites and is appropriate for evaluation of long-term or chronic effects. This scale also includes the characteristic concentrations for other areas with dimensions of a few hundred meters such as the parking lot and feeder streets associated with shopping centers, stadia, and office buildings.
(3) Neighborhood scale--Measurements in this category would represent conditions throughout some reasonably homogeneous urban sub-region with dimensions of a few kilometers and of generally more regular shape than the middle scale. Homogeneity refers to the particulate matter concentrations, as well as the land use and land surface characteristics. Much of the PM 2.5 exposures are expected to be associated with this scale of measurement. In some cases, a location carefully chosen to provide neighborhood scale data would represent the immediate neighborhood as well as neighborhoods of the same type in other parts of the city. PM 2.5 sites of this kind provide good information about trends and compliance with standards because they often represent conditions in areas where people commonly live and work for periods comparable to those specified in the NAAQS. In general, most PM 2.5 monitoring in urban areas should have this scale.
(4) Urban scale--This class of measurement would be used to characterize the particulate matter concentration over an entire metropolitan or rural area ranging in size from 4 to 50 kilometers. Such measurements would be useful for assessing trends in area-wide air quality, and hence, the effectiveness of large scale air pollution control strategies. Community-oriented PM 2.5 sites may have this scale.
(5) Regional scale--These measurements would characterize conditions over areas with dimensions of as much as hundreds of kilometers. As noted earlier, using representative conditions for an area implies some degree of homogeneity in that area. For this reason, regional scale measurements would be most applicable to sparsely populated areas. Data characteristics of this scale would provide information about larger scale processes of particulate matter emissions, losses and transport. PM 2.5 transport contributes to elevated particulate concentrations and may affect multiple urban and State entities with large populations such as in the eastern United States. Development of effective pollution control strategies requires an understanding at regional geographical scales of the emission sources and atmospheric processes that are responsible for elevated PM 2.5 levels and may also be associated with elevated O3 and regional haze.
4.7.2 Requirement for Continuous PM 2.5 Monitoring. The State, or where appropriate, local agencies must operate continuous PM 2.5 analyzers equal to at least one-half (round up) the minimum required sites listed in Table D-5 of this appendix. At least one required continuous analyzer in each MSA must be collocated with one of the required FRM/FEM/ARM monitors, unless at least one of the required FRM/FEM/ARM monitors is itself a continuous FEM or ARM monitor in which case no collocation requirement applies. State and local air monitoring agencies must use methodologies and quality assurance/quality control (QA/QC) procedures approved by the EPA Regional Administrator for these required continuous analyzers.
4.7.3 Requirement for PM 2.5 Background and Transport Sites. Each State shall install and operate at least one PM 2.5 site to monitor for regional background and at least one PM 2.5 site to monitor regional transport. These monitoring sites may be at community-oriented sites and this requirement may be satisfied by a corresponding monitor in an area having similar air quality in another State. State and local air monitoring agencies must use methodologies and QA/QC procedures approved by the EPA Regional Administrator for these sites. Methods used at these sites may include non-federal reference method samplers such as IMPROVE or continuous PM 2.5 monitors.
4.7.4 PM 2.5 Chemical Speciation Site Requirements. Each State shall continue to conduct chemical speciation monitoring and analyses at sites designated to be part of the PM 2.5 Speciation Trends Network (STN). The selection and modification of these STN sites must be approved by the Administrator. The PM 2.5 chemical speciation urban trends sites shall include analysis for elements, selected anions and cations, and carbon. Samples must be collected using the monitoring methods and the sampling schedules approved by the Administrator. Chemical speciation is encouraged at additional sites where the chemically resolved data would be useful in developing State implementation plans and supporting atmospheric or health effects related studies.
4.8 Coarse Particulate Matter (PM 10-2.5) Design Criteria.
(a) The only required monitors for PM 10-2.5 are those required at NCore Stations.
(b) Although microscale monitoring may be appropriate in some circumstances, middle and neighborhood scale measurements are the most important station classifications for PM 10-2.5 to assess the variation in coarse particle concentrations that would be expected across populated areas that are in proximity to large emissions sources.
(1) Microscale--This scale would typify relatively small areas immediately adjacent to: Industrial sources; locations experiencing ongoing construction, redevelopment, and soil disturbance; and heavily traveled roadways. Data collected at microscale stations would characterize exposure over areas of limited spatial extent and population exposure, and may provide information useful for evaluating and developing source-oriented control measures.
(2) Middle scale--People living or working near major roadways or industrial districts encounter particle concentrations that would be adequately characterized by this spatial scale. Thus, measurements of this type would be appropriate for the evaluation of public health effects of coarse particle exposure. Monitors located in populated areas that are nearly adjacent to large industrial point sources of coarse particles provide suitable locations for assessing maximum population exposure levels and identifying areas of potentially poor air quality. Similarly, monitors located in populated areas that border dense networks of heavily-traveled traffic are appropriate for assessing the impacts of resuspended road dust. This scale also includes the characteristic concentrations for other areas with dimensions of a few hundred meters such as school grounds and parks that are nearly adjacent to major roadways and industrial point sources, locations exhibiting mixed residential and commercial development, and downtown areas featuring office buildings, shopping centers, and stadiums.
(3) Neighborhood scale--Measurements in this category would represent conditions throughout some reasonably homogeneous urban sub-region with dimensions of a few kilometers and of generally more regular shape than the middle scale. Homogeneity refers to the particulate matter concentrations, as well as the land use and land surface characteristics. This category includes suburban neighborhoods dominated by residences that are somewhat distant from major roadways and industrial districts but still impacted by urban sources, and areas of diverse land use where residences are interspersed with commercial and industrial neighborhoods. In some cases, a location carefully chosen to provide neighborhood scale data would represent the immediate neighborhood as well as neighborhoods of the same type in other parts of the city. The comparison of data from middle scale and neighborhood scale sites would provide valuable information for determining the variation of PM 10-2.5 levels across urban areas and assessing the spatial extent of elevated concentrations caused by major industrial point sources and heavily traveled roadways. Neighborhood scale sites would provide concentration data that are relevant to informing a large segment of the population of their exposure levels on a given day.
4.8.2 [Reserved]
5. Network Design for Photochemical Assessment Monitoring Stations
(PAMS)
The PAMS program provides more comprehensive data on O3 air pollution in areas classified as serious, severe, or extreme nonattainment for O3 than would otherwise be achieved through the NCore and SLAMS sites. More specifically, the PAMS program includes measurements for O3, oxides of nitrogen, VOC, and meteorology.
5.1 PAMS Monitoring Objectives. PAMS design criteria are site specific. Concurrent measurements of O3, oxides of nitrogen, speciated VOC, CO, and meteorology are obtained at PAMS sites. Design criteria for the PAMS network are based on locations relative to O3 precursor source areas and predominant wind directions associated with high O3 events. Specific monitoring objectives are associated with each location. The overall design should enable characterization of precursor emission sources within the area, transport of O3 and its precursors, and the photochemical processes related to O3 nonattainment. Specific objectives that must be addressed include assessing ambient trends in O3, oxides of nitrogen, VOC species, and determining spatial and diurnal variability of O3, oxides of nitrogen, and VOC species. Specific monitoring objectives associated with each of these sites may result in four distinct site types. Detailed guidance for the locating of these sites may be found in reference 9 of this appendix.
(a) Type 1 sites are established to characterize upwind background and transported O3 and its precursor concentrations entering the area and will identify those areas which are subjected to transport.
(b) Type 2 sites are established to monitor the magnitude and type of precursor emissions in the area where maximum precursor emissions are expected to impact and are suited for the monitoring of urban air toxic pollutants.
(c) Type 3 sites are intended to monitor maximum O3 concentrations occurring downwind from the area of maximum precursor emissions.
(d) Type 4 sites are established to characterize the downwind transported O3 and its precursor concentrations exiting the area and will identify those areas which are potentially contributing to overwhelming transport in other areas.
5.2 Monitoring Period. PAMS precursor monitoring must be conducted annually throughout the months of June, July and August (as a minimum) when peak O3 values are expected in each area. Alternate precursor monitoring periods may be submitted for approval to the Administrator as a part of the annual monitoring network plan required by Sec. 58.10.
5.3 Minimum Monitoring Network Requirements. A Type 2 site is required for each area. Overall, only two sites are required for each area, providing all chemical measurements are made. For example, if a design includes two Type 2 sites, then a third site will be necessary to capture the NOy measurement. The minimum required number and type of monitoring sites and sampling requirements are listed in Table D-6 of this appendix. Any alternative plans may be put in place in lieu of these requirements, if approved by the Administrator.
Table D-6 of Appendix D to Part 58--Minimum Required PAMS Monitoring
Locations and Frequencies------------------------------------------------------------------------
Sampling frequency
(all daily except for
Measurement Where required upper air
meteorology) \1\------------------------------------------------------------------------Speciated VOC \2\......... Two sites per area, During the PAMS
one of which must be monitoring period:
(1) Hourly auto GC,
or (2) Eight 3-hour
canisters, or (3) 1
morning and 1
afternoon canister
with a 3-hour or
less averaging time
plus Continuous
Total Non-methane
Hydrocarbon
measurement.Carbonyl sampling......... Type 2 site in areas 3-hour samples every
classified as day during the PAMS
serious or above for monitoring period.
the 8-hour ozone
standard.NOX....................... All Type 2 sites..... Hourly during the
ozone monitoring
season.\3\NOy....................... One site per area at Hourly during the
the Type 3 or Type 1 ozone monitoring
site. season.CO (ppb level)............ One site per area at Hourly during the
a Type 2 site. ozone monitoring
season.Ozone..................... All sites............ Hourly during the
ozone monitoring
season.Surface met............... All sites............ Hourly during the
ozone monitoring
season.Upper air meteorology..... One representative Sampling frequency
location within PAMS must be approved as
area. part of the annual
monitoring network
plan required in 40
CFR 58.10.------------------------------------------------------------------------\1\ Daily or with an approved alternative plan.\2\ Speciated VOC is defined in the ``Technical Assistance Document for
Sampling and Analysis of Ozone Precursors'', EPA/600-R-98/161,
September 1998.\3\ Approved ozone monitoring season as stipulated in Table D-3 of this
appendix.
5.4 Transition Period. A transition period is allowed for phasing in the operation of newly required PAMS programs (due generally to reclassification of an area into serious, severe, or extreme nonattainment for ozone). Following the date of redesignation or reclassification of any existing O3 nonattainment area to serious, severe, or extreme, or the designation of a new area and classification to serious, severe, or extreme O3 nonattainment, a State is allowed 1 year to develop plans for its PAMS implementation strategy. Subsequently, a minimum of one Type 2 site must be operating by the first month of the following approved PAMS season. Operation of the remaining site(s) must, at a minimum, be phased in at the rate of one site per year during subsequent years as outlined in the approved PAMS network description provided by the State.
6. References
1. Ball, R.J. and G.E. Anderson. Optimum Site Exposure Criteria for SO2 Monitoring. The Center for the Environment and Man, Inc., Hartford, CT. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-77-013. April 1977.
2. Ludwig, F.F., J.H.S. Kealoha, and E. Shelar. Selecting Sites for Carbon Monoxide Monitoring. Stanford Research Institute, Menlo Park, CA. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-75-077, September 1975.
3. Air Quality Criteria for Lead. Office of Research and Development, U.S. Environmental Protection Agency, Washington D.C. EPA Publication No. 600/8-89-049F. August 1990. (NTIS document numbers PB87-142378 and PB91-138420.)
4. Optimum Site Exposure Criteria for Lead Monitoring. PEDCo Environmental, Inc. Cincinnati, OH. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-02-3013. May 1981.
5. Guidance for Conducting Ambient Air Monitoring for Lead Around Point Sources. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA-454/R-92-009. May 1997.
6. Koch, R.C. and H.E. Rector. Optimum Network Design and Site Exposure Criteria for Particulate Matter. GEOMET Technologies, Inc., Rockville, MD. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-87-009. May 1987.
7. Watson et al. Guidance for Network Design and Optimum Site Exposure for PM 2.5 and PM 10. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA-454/R-99-022, December 1997.
8. Guideline for Selecting and Modifying the Ozone Monitoring Season Based on an 8-Hour Ozone Standard. Prepared for U.S. Environmental Protection Agency, RTP, NC. EPA-454/R-98-001, June 1998.
9. Photochemical Assessment Monitoring Stations Implementation Manual. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA-454/B-93-051. March 1994. [71 FR 61316, Oct. 17, 2006, as amended at 72 FR 32211, June 12, 2007; 73 FR 67062, Nov. 12, 2008; 75 FR 6534, Feb. 9, 2010; 75 FR 35602, June 22, 2010; 75 FR 81137, Dec. 27, 2010; 76 FR 54342, Aug. 31, 2011; 78 FR 3284, Jan. 15, 2013]
Sec. Appendix E to Part 58--Probe and Monitoring Path Siting Criteria
for Ambient Air Quality Monitoring 1. Introduction.2. Horizontal and Vertical Placement.3. Spacing from Minor Sources.4. Spacing From Obstructions.5. Spacing From Trees.6. Spacing From Roadways.7. Cumulative Interferences on a Monitoring Path.8. Maximum Monitoring Path Length.9. Probe Material and Pollutant Sample Residence Time.10. Waiver Provisions.11. Summary.12. References.
1. Introduction
(a) This appendix contains specific location criteria applicable to SLAMS, NCore, and PAMS ambient air quality monitoring probes, inlets, and optical paths after the general location has been selected based on the monitoring objectives and spatial scale of representation discussed in appendix D to this part. Adherence to these siting criteria is necessary to ensure the uniform collection of compatible and comparable air quality data.
(b) The probe and monitoring path siting criteria discussed in this appendix must be followed to the maximum extent possible. It is recognized that there may be situations where some deviation from the siting criteria may be necessary. In any such case, the reasons must be thoroughly documented in a written request for a waiver that describes how and why the proposed siting deviates from the criteria. This documentation should help to avoid later questions about the validity of the resulting monitoring data. Conditions under which the EPA would consider an application for waiver from these siting criteria are discussed in section 10 of this appendix.
(c) The pollutant-specific probe and monitoring path siting criteria generally apply to all spatial scales except where noted otherwise. Specific siting criteria that are phrased with a ``must'' are defined as requirements and exceptions must be approved through the waiver provisions. However, siting criteria that are phrased with a ``should'' are defined as goals to meet for consistency but are not requirements.
2. Horizontal and Vertical Placement
The probe or at least 80 percent of the monitoring path must be located between 2 and 15 meters above ground level for all O3 and SO2 monitoring sites, and for neighborhood or larger spatial scale Pb, PM 10, PM 10-2.5, PM 2.5, NO2, and CO sites. Middle scale PM 10-2.5 sites are required to have sampler inlets between 2 and 7 meters above ground level. Microscale Pb, PM 10, PM 10-2.5, and PM 2.5 sites are required to have sampler inlets between 2 and 7 meters above ground level. Microscale near-road NO2 monitoring sites are required to have sampler inlets between 2 and 7 meters above ground level. The inlet probes for microscale carbon monoxide monitors that are being used to measure concentrations near roadways must be between 2 and 7 meters above ground level. Those inlet probes for microscale carbon monoxide monitors measuring concentrations near roadways in downtown areas or urban street canyons must be between 2.5 and 3.5 meters above ground level. The probe or at least 90 percent of the monitoring path must be at least 1 meter vertically or horizontally away from any supporting structure, walls, parapets, penthouses, etc., and away from dusty or dirty areas. If the probe or a significant portion of the monitoring path is located near the side of a building or wall, then it should be located on the windward side of the building relative to the prevailing wind direction during the season of highest concentration potential for the pollutant being measured.
3. Spacing From Minor Sources
(a) It is important to understand the monitoring objective for a particular location in order to interpret this particular requirement. Local minor sources of a primary pollutant, such as SO2, lead, or particles, can cause high concentrations of that particular pollutant at a monitoring site. If the objective for that monitoring site is to investigate these local primary pollutant emissions, then the site is likely to be properly located nearby. This type of monitoring site would in all likelihood be a microscale type of monitoring site. If a monitoring site is to be used to determine air quality over a much larger area, such as a neighborhood or city, a monitoring agency should avoid placing a monitor probe, path, or inlet near local, minor sources. The plume from the local minor sources should not be allowed to inappropriately impact the air quality data collected at a site. Particulate matter sites should not be located in an unpaved area unless there is vegetative ground cover year round, so that the impact of wind blown dusts will be kept to a minimum.
(b) Similarly, local sources of nitric oxide (NO) and ozone-reactive hydrocarbons can have a scavenging effect causing unrepresentatively low concentrations of O3 in the vicinity of probes and monitoring paths for O3. To minimize these potential interferences, the probe or at least 90 percent of the monitoring path must be away from furnace or incineration flues or other minor sources of SO2 or NO. The separation distance should take into account the heights of the flues, type of waste or fuel burned, and the sulfur content of the fuel.
4. Spacing From Obstructions
(a) Buildings and other obstacles may possibly scavenge SO2, O3, or NO2, and can act to restrict airflow for any pollutant. To avoid this interference, the probe, inlet, or at least 90 percent of the monitoring path must have unrestricted airflow and be located away from obstacles. The distance from the obstacle to the probe, inlet, or monitoring path must be at least twice the height that the obstacle protrudes above the probe, inlet, or monitoring path. An exception to this requirement can be made for measurements taken in street canyons or at source-oriented sites where buildings and other structures are unavoidable.
(b) Generally, a probe or monitoring path located near or along a vertical wall is undesirable because air moving along the wall may be subject to possible removal mechanisms. A probe, inlet, or monitoring path must have unrestricted airflow in an arc of at least 180 degrees. This arc must include the predominant wind direction for the season of greatest pollutant concentration potential. For particle sampling, a minimum of 2 meters of separation from walls, parapets, and structures is required for rooftop site placement.
(c) Special consideration must be given to the use of open path analyzers due to their inherent potential sensitivity to certain types of interferences, or optical obstructions. A monitoring path must be clear of all trees, brush, buildings, plumes, dust, or other optical obstructions, including potential obstructions that may move due to wind, human activity, growth of vegetation, etc. Temporary optical obstructions, such as rain, particles, fog, or snow, should be considered when siting an open path analyzer. Any of these temporary obstructions that are of sufficient density to obscure the light beam will affect the ability of the open path analyzer to continuously measure pollutant concentrations. Transient, but significant obscuration of especially longer measurement paths could occur as a result of certain meteorological conditions (e.g., heavy fog, rain, snow) and/or aerosol levels that are of a sufficient density to prevent the open path analyzer's light transmission. If certain compensating measures are not otherwise implemented at the onset of monitoring (e.g., shorter path lengths, higher light source intensity), data recovery during periods of greatest primary pollutant potential could be compromised. For instance, if heavy fog or high particulate levels are coincident with periods of projected NAAQS-threatening pollutant potential, the representativeness of the resulting data record in reflecting maximum pollutant concentrations may be substantially impaired despite the fact that the site may otherwise exhibit an acceptable, even exceedingly high overall valid data capture rate.
(d) For near-road NO2 monitoring stations, the monitor probe shall have an unobstructed air flow, where no obstacles exist at or above the height of the monitor probe, between the monitor probe and the outside nearest edge of the traffic lanes of the target road segment.
5. Spacing From Trees
(a) Trees can provide surfaces for SO2, O3, or NO2 adsorption or reactions, and surfaces for particle deposition. Trees can also act as obstructions in cases where they are located between the air pollutant sources or source areas and the monitoring site, and where the trees are of a sufficient height and leaf canopy density to interfere with the normal airflow around the probe, inlet, or monitoring path. To reduce this possible interference/obstruction, the probe, inlet, or at least 90 percent of the monitoring path must be at least 10 meters or further from the drip line of trees.
(b) The scavenging effect of trees is greater for O3 than for other criteria pollutants. Monitoring agencies must take steps to consider the impact of trees on ozone monitoring sites and take steps to avoid this problem.
(c) For microscale sites of any air pollutant, no trees or shrubs should be located between the probe and the source under investigation, such as a roadway or a stationary source.
6. Spacing From Roadways
Table E-1 of Appendix E to Part 58--Minimum Separation Distance Between
Roadways and Probes or Monitoring Paths for Monitoring Neighborhood and
Urban Scale Ozone (O3) and Oxides of Nitrogen (NO, NO2, NOX, NOy)------------------------------------------------------------------------
Minimum Minimum
Roadway average daily traffic, vehicles per distance \1\ distance \1
day (meters) 2\ (meters)------------------------------------------------------------------------41,000...................................... 10 1010,000...................................... 10 2015,000...................................... 20 3020,000...................................... 30 4040,000...................................... 50 6070,000...................................... 100 100"110,000.................................... 250 250------------------------------------------------------------------------\1\ Distance from the edge of the nearest traffic lane. The distance for
intermediate traffic counts should be interpolated from the table
values based on the actual traffic count.\2\ Applicable for ozone monitors whose placement has not already been
approved as of December 18, 2006.
6.1 Spacing for Ozone Probes and Monitoring Paths
In siting an O3 analyzer, it is important to minimize destructive interferences form sources of NO, since NO readily reacts with O3. Table E-1 of this appendix provides the required minimum separation distances between a roadway and a probe or, where applicable, at least 90 percent of a monitoring path for various ranges of daily roadway traffic. A sampling site having a point analyzer probe located closer to a roadway than allowed by the Table E-1 requirements should be classified as microscale or middle scale, rather than neighborhood or urban scale, since the measurements from such a site would more closely represent the middle scale. If an open path analyzer is used at a site, the monitoring path(s) must not cross over a roadway with an average daily traffic count of 10,000 vehicles per day or more. For those situations where a monitoring path crosses a roadway with fewer than 10,000 vehicles per day, monitoring agencies must consider the entire segment of the monitoring path in the area of potential atmospheric interference from automobile emissions. Therefore, this calculation must include the length of the monitoring path over the roadway plus any segments of the monitoring path that lie in the area between the roadway and minimum separation distance, as determined from the Table E-1 of this appendix. The sum of these distances must not be greater than 10 percent of the total monitoring path length.
(a) Near-road microscale CO monitoring sites, including those located in downtown areas, urban street canyons, and other near-road locations such as those adjacent to highly trafficked roads, are intended to provide a measurement of the influence of the immediate source on the pollution exposure on the adjacent area.
(b) Microscale CO monitor inlets probes in downtown areas or urban street canyon locations shall be located a minimum distance of 2 meters and a maximum distance of 10 meters from the edge of the nearest traffic lane.
(c) Microscale CO monitor inlet probes in downtown areas or urban street canyon locations shall be located at least 10 meters from an intersection and preferably at a midblock location. Midblock locations are preferable to intersection locations because intersections represent a much smaller portion of downtown space than do the streets between them. Pedestrian exposure is probably also greater in street canyon/corridors than at intersections.
Table E-2 of Appendix E to Part 58--Minimum Separation Distance Between
Roadways and Probes or Monitoring Paths for Monitoring Neighborhood
Scale Carbon Monoxide------------------------------------------------------------------------
Minimum
Roadway average daily traffic, vehicles per day distance \1\
(meters)------------------------------------------------------------------------410,000................................................. 1015,000.................................................. 2520,000.................................................. 4530,000.................................................. 8040,000.................................................. 11550,000.................................................. 135"60,000................................................. 150------------------------------------------------------------------------\1\ Distance from the edge of the nearest traffic lane. The distance for
intermediate traffic counts should be interpolated from the table
values based on the actual traffic count.
(a) Since emissions associated with the operation of motor vehicles contribute to urban area particulate matter ambient levels, spacing from roadway criteria are necessary for ensuring national consistency in PM sampler siting.
(b) The intent is to locate localized hot-spot sites in areas of highest concentrations whether it be from mobile or multiple stationary sources. If the area is primarily affected by mobile sources and the maximum concentration area(s) is judged to be a traffic corridor or street canyon location, then the monitors should be located near roadways with the highest traffic volume and at separation distances most likely to produce the highest concentrations. For the microscale traffic corridor site, the location must be between 5 and 15 meters from the major roadway. For the microscale street canyon site the location must be between 2 and 10 meters from the roadway. For the middle scale site, a range of acceptable distances from the roadway is shown in figure E-1 of this appendix. This figure also includes separation distances between a roadway and neighborhood or larger scale sites by default. Any site, 2 to 15 meters high, and further back than the middle scale requirements will generally be neighborhood, urban or regional scale. For example, according to Figure E-1 of this appendix, if a PM sampler is primarily influenced by roadway emissions and that sampler is set back 10 meters from a 30,000 ADT (average daily traffic) road, the site should be classified as microscale, if the sampler height is between 2 and 7 meters. If the sampler height is between 7 and 15 meters, the site should be classified as middle scale. If the sample is 20 meters from the same road, it will be classified as middle scale; if 40 meters, neighborhood scale; and if 110 meters, an urban scale.
6.4 Spacing for Nitrogen Dioxide (NO2) Probes and Monitoring Paths.
(a) In siting near-road NO2 monitors as required in paragraph 4.3.2 of appendix D of this part, the monitor probe shall be as near as practicable to the outside nearest edge of the traffic lanes of the target road segment; but shall not be located at a distance greater than 50 meters, in the horizontal, from the outside nearest edge of the traffic lanes of the target road segment.
(b) In siting NO2 monitors for neighborhood and larger scale monitoring, it is important to minimize near-road influences. Table E-1 of this appendix provides the required minimum separation distances between a roadway and a probe or, where applicable, at least 90 percent of a monitoring path for various ranges of daily roadway traffic. A sampling site having a point analyzer probe located closer to a roadway than allowed by the Table E-1 requirements should be classified as microscale or middle scale rather than neighborhood or urban scale. If an open path analyzer is used at a site, the monitoring path(s) must not cross over a roadway with an average daily traffic count of 10,000 vehicles per day or more. For those situations where a monitoring path crosses a roadway with fewer than 10,000 vehicles per day, monitoring agencies must consider the entire segment of the monitoring path in the area of potential atmospheric interference form automobile emissions. Therefore, this calculation must include the length of the monitoring path over the roadway plus any segments of the monitoring path that lie in the area between the roadway and minimum separation distance, as determined form the Table E-1 of this appendix. The sum of these distances must not be greater than 10 percent of the total monitoring path length. [GRAPHIC] [TIFF OMITTED] TR17OC06.061
7. Cumulative Interferences on a Monitoring Path
(This paragraph applies only to open path analyzers.) The cumulative length or portion of a monitoring path that is affected by minor sources, trees, or roadways must not exceed 10 percent of the total monitoring path length.
8. Maximum Monitoring Path Length
(This paragraph applies only to open path analyzers.) The monitoring path length must not exceed 1 kilometer for analyzers in neighborhood, urban, or regional scale. For middle scale monitoring sites, the monitoring path length must not exceed 300 meters. In areas subject to frequent periods of dust, fog, rain, or snow, consideration should be given to a shortened monitoring path length to minimize loss of monitoring data due to these temporary optical obstructions. For certain ambient air monitoring scenarios using open path analyzers, shorter path lengths may be needed in order to ensure that the monitoring site meets the objectives and spatial scales defined in appendix D to this part. The Regional Administrator may require shorter path lengths, as needed on an individual basis, to ensure that the SLAMS sites meet the appendix D requirements. Likewise, the Administrator may specify the maximum path length used at NCore monitoring sites.
9. Probe Material and Pollutant Sample Residence Time
(a) For the reactive gases, SO2, NO2, and O3, special probe material must be used for point analyzers. Studies \20-24\ have been conducted to determine the suitability of materials such as polypropylene, polyethylene, polyvinyl chloride, Tygon [supreg], aluminum, brass, stainless steel, copper, Pyrex [supreg] glass and Teflon [supreg] for use as intake sampling lines. Of the above materials, only Pyrex [supreg] glass and Teflon [supreg] have been found to be acceptable for use as intake sampling lines for all the reactive gaseous pollutants. Furthermore, the EPA \25\ has specified borosilicate glass or FEP Teflon [supreg] as the only acceptable probe materials for delivering test atmospheres in the determination of reference or equivalent methods. Therefore, borosilicate glass, FEP Teflon [supreg] or their equivalent must be the only material in the sampling train (from inlet probe to the back of the analyzer) that can be in contact with the ambient air sample for existing and new SLAMs.
(b) For volatile organic compound (VOC) monitoring at PAMS, FEP Teflon [supreg] is unacceptable as the probe material because of VOC adsorption and desorption reactions on the FEP Teflon [supreg]. Borosilicate glass, stainless steel, or its equivalent are the acceptable probe materials for VOC and carbonyl sampling. Care must be taken to ensure that the sample residence time is kept to 20 seconds or less.
(c) No matter how nonreactive the sampling probe material is initially, after a period of use reactive particulate matter is deposited on the probe walls. Therefore, the time it takes the gas to transfer from the probe inlet to the sampling device is also critical. Ozone in the presence of nitrogen oxide (NO) will show significant losses even in the most inert probe material when the residence time exceeds 20 seconds. \26\ Other studies \27 28\ indicate that a 10 second or less residence time is easily achievable. Therefore, sampling probes for reactive gas monitors at NCore and at NO2 sites must have a sample residence time less than 20 seconds.
10. Waiver Provisions
Most sampling probes or monitors can be located so that they meet the requirements of this appendix. New sites with rare exceptions, can be located within the limits of this appendix. However, some existing sites may not meet these requirements and still produce useful data for some purposes. The EPA will consider a written request from the State agency to waive one or more siting criteria for some monitoring sites providing that the State can adequately demonstrate the need (purpose) for monitoring or establishing a monitoring site at that location.
10.1 For establishing a new site, a waiver may be granted only if both of the following criteria are met:
10.1.1 The site can be demonstrated to be as representative of the monitoring area as it would be if the siting criteria were being met.
10.1.2 The monitor or probe cannot reasonably be located so as to meet the siting criteria because of physical constraints (e.g., inability to locate the required type of site the necessary distance from roadways or obstructions).
10.2 However, for an existing site, a waiver may be granted if either of the criteria in sections 10.1.1 and 10.1.2 of this appendix are met.
10.3 Cost benefits, historical trends, and other factors may be used to add support to the criteria in sections 10.1.1 and 10.1.2 of this appendix, however, they in themselves, will not be acceptable reasons for granting a waiver. Written requests for waivers must be submitted to the Regional Administrator.
11. Summary
Table E-4 of this appendix presents a summary of the general requirements for probe and monitoring path siting criteria with respect to distances and heights. It is apparent from Table E-4 that different elevation distances above the ground are shown for the various pollutants. The discussion in this appendix for each of the pollutants describes reasons for elevating the monitor, probe, or monitoring path. The differences in the specified range of heights are based on the vertical concentration gradients. For CO and near-road NO2 monitors, the gradients in the vertical direction are very large for the microscale, so a small range of heights are used. The upper limit of 15 meters is specified for the consistency between pollutants and to allow the use of a single manifold or monitoring path for monitoring more than one pollutant.
Table E-4 of Appendix E to Part 58--Summary of Probe and Monitoring Path Siting Criteria--------------------------------------------------------------------------------------------------------------------------------------------------------
Horizontal and
vertical distance
Scale (maximum Height from ground to from supporting Distance from trees Distance from
Pollutant monitoring path probe, inlet or 80% of structures \2\ to to probe, inlet or roadways to probe,
length, meters) monitoring path \1\ probe, inlet or 90% 90% of monitoring inlet or monitoring
(meters) of monitoring path path \1\ (meters) path \1\ (meters)
\1\ (meters)--------------------------------------------------------------------------------------------------------------------------------------------------------SO2 \3 4 5 6\...................... Middle (300 m) 2-15.................. 41................... 410.................. N/A.
Neighborhood Urban,
and Regional (1 km).CO \4 5 7\......................... Micro [downtown or 2.5-3.5; 2-7; 2-15.... 41................... 410.................. 2-10 for downtown
street canyon sites], areas or street
micro [near-road canyon microscale;
sites], middle (300 450 for near-road
m) and Neighborhood microscale; see
(1 km). Table E-2 of this
appendix for middle
and neighborhood
scales.O 3 \3 4 5\........................ Middle (300 m) 2-15.................. 41................... 410.................. See Table E-1 of this
Neighborhood, Urban, appendix for all
and Regional (1 km). scales.
NO2 \3 4 5\........................ Micro (Near-road [50- 2-7 (micro);.......... >1................... >10.................. 450 for near-road
300 m]). micro-scale.
Middle (300 m)........ 2-15 (all other
scales).
Neighborhood, Urban, ...................... ..................... ..................... See Table E-1 of this
and Regional (1 km). appendix for all
other scales.Ozone precursors (for PAMS) \3 4 5\ Neighborhood and Urban 2-15.................. >1................... >10.................. See Table E-4 of this
(1 km). appendix for all
scales.PM, Pb \3 4 5 8\................... Micro, Middle, 2-7 (micro); 2-7 >2 (all scales, >10 (all scales)..... 2-10 (micro); see
Neighborhood, Urban (middle PM 10 2.5); 2- horizontal distance Figure E-1 of this
and Regional. 7 for near-road; 2-15 only). appendix for all
(all other scales). other scales. 450
for near-road.--------------------------------------------------------------------------------------------------------------------------------------------------------N/A--Not applicable.\1\ Monitoring path for open path analyzers is applicable only to middle or neighborhood scale CO monitoring, middle, neighborhood, urban, and regional
scale NO2 monitoring, and all applicable scales for monitoring SO2, O3, and O3 precursors.\2\ When probe is located on a rooftop, this separation distance is in reference to walls, parapets, or penthouses located on roof.\3\ Should be greater than 20 meters from the dripline of tree(s) and must be 10 meters from the dripline when the tree(s) act as an obstruction.\4\ Distance from sampler, probe, or 90 percent of monitoring path to obstacle, such as a building, must be at least twice the height the obstacle
protrudes above the sampler, probe, or monitoring path. Sites not meeting this criterion may be classified as middle scale (see text).\5\ Must have unrestricted airflow 270 degrees around the probe or sampler; 180 degrees if the probe is on the side of a building or a wall.\6\ The probe, sampler, or monitoring path should be away from minor sources, such as furnace or incineration flues. The separation distance is
dependent on the height of the minor source's emission point (such as a flue), the type of fuel or waste burned, and the quality of the fuel (sulfur,
ash, or lead content). This criterion is designed to avoid undue influences from minor sources.\7\ For micro-scale CO monitoring sites, the probe must be 410 meters from a street intersection and preferably at a midblock location.\8\ Collocated monitors must be within 4 meters of each other and at least 2 meters apart for flow rates greater than 200 liters/min or at least 1 meter
apart for samplers having flow rates less than 200 liters/min to preclude airflow interference, unless a waiver is in place as approved by the
Regional Administrator pursuant to section 3 of Appendix A.
12. References
1. Bryan, R.J., R.J. Gordon, and H. Menck. Comparison of High Volume Air Filter Samples at Varying Distances from Los Angeles Freeway. University of Southern California, School of Medicine, Los Angeles, CA. (Presented at 66th Annual Meeting of Air Pollution Control Association. Chicago, IL. June 24-28, 1973. APCA 73-158.)
2. Teer, E.H. Atmospheric Lead Concentration Above an Urban Street. Master of Science Thesis, Washington University, St. Louis, MO. January 1971.
3. Bradway, R.M., F.A. Record, and W.E. Belanger. Monitoring and Modeling of Resuspended Roadway Dust Near Urban Arterials. GCA Technology Division, Bedford, MA. (Presented at 1978 Annual Meeting of Transportation Research Board, Washington, DC. January 1978.)
4. Pace, T.G., W.P. Freas, and E.M. Afify. Quantification of Relationship Between Monitor Height and Measured Particulate Levels in Seven U.S. Urban Areas. U.S. Environmental Protection Agency, Research Triangle Park, NC. (Presented at 70th Annual Meeting of Air Pollution Control Association, Toronto, Canada. June 20-24, 1977. APCA 77-13.4.)
5. Harrison, P.R. Considerations for Siting Air Quality Monitors in Urban Areas. City of Chicago, Department of Environmental Control, Chicago, IL. (Presented at 66th Annual Meeting of Air Pollution Control Association, Chicago, IL. June 24-28, 1973. APCA 73-161.)
6. Study of Suspended Particulate Measurements at Varying Heights Above Ground. Texas State Department of Health, Air Control Section, Austin, TX. 1970. p.7.
7. Rodes, C.E. and G.F. Evans. Summary of LACS Integrated Pollutant Data. In: Los Angeles Catalyst Study Symposium. U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-600/4-77-034. June 1977.
8. Lynn, D.A. et al. National Assessment of the Urban Particulate Problem: Volume 1, National Assessment. GCA Technology Division, Bedford, MA. U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-75-024. June 1976.
9. Pace, T.G. Impact of Vehicle-Related Particulates on TSP Concentrations and Rationale for Siting Hi-Vols in the Vicinity of Roadways. OAQPS, U.S. Environmental Protection Agency, Research Triangle Park, NC. April 1978.
10. Ludwig, F.L., J.H. Kealoha, and E. Shelar. Selecting Sites for Monitoring Total Suspended Particulates. Stanford Research Institute, Menlo Park, CA. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-77-018. June 1977, revised December 1977.
11. Ball, R.J. and G.E. Anderson. Optimum Site Exposure Criteria for SO2 Monitoring. The Center for the Environment and Man, Inc., Hartford, CT. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-77-013. April 1977.
12. Ludwig, F.L. and J.H.S. Kealoha. Selecting Sites for Carbon Monoxide Monitoring. Stanford Research Institute, Menlo Park, CA. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-75-077. September 1975.
13. Ludwig, F.L. and E. Shelar. Site Selection for the Monitoring of Photochemical Air Pollutants. Stanford Research Institute, Menlo Park, CA. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Publication No. EPA-450/3-78-013. April 1978.
14. Lead Analysis for Kansas City and Cincinnati, PEDCo Environmental, Inc., Cincinnati, OH. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 66-02-2515, June 1977.
15. Barltrap, D. and C.D. Strelow. Westway Nursery Testing Project. Report to the Greater London Council. August 1976.
16. Daines, R. H., H. Moto, and D. M. Chilko. Atmospheric Lead: Its Relationship to Traffic Volume and Proximity to Highways. Environ. Sci. and Technol., 4:318, 1970.
17. Johnson, D. E., et al. Epidemiologic Study of the Effects of Automobile Traffic on Blood Lead Levels, Southwest Research Institute, Houston, TX. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA-600/1-78-055, August 1978.
18. Air Quality Criteria for Lead. Office of Research and Development, U.S. Environmental Protection Agency, Washington, DC EPA-600/8-83-028 aF-dF, 1986, and supplements EPA-600/8-89/049F, August 1990. (NTIS document numbers PB87-142378 and PB91-138420.)
19. Lyman, D. R. The Atmospheric Diffusion of Carbon Monoxide and Lead from an Expressway, Ph.D. Dissertation, University of Cincinnati, Cincinnati, OH. 1972.
20. Wechter, S.G. Preparation of Stable Pollutant Gas Standards Using Treated Aluminum Cylinders. ASTM STP. 598:40-54, 1976.
21. Wohlers, H.C., H. Newstein and D. Daunis. Carbon Monoxide and Sulfur Dioxide Adsorption On and Description From Glass, Plastic and Metal Tubings. J. Air Poll. Con. Assoc. 17:753, 1976.
22. Elfers, L.A. Field Operating Guide for Automated Air Monitoring Equipment. U.S. NTIS. p. 202, 249, 1971.
23. Hughes, E.E. Development of Standard Reference Material for Air Quality Measurement. ISA Transactions, 14:281-291, 1975.
24. Altshuller, A.D. and A.G. Wartburg. The Interaction of Ozone with Plastic and Metallic Materials in a Dynamic Flow System. Intern. Jour. Air and Water Poll., 4:70-78, 1961.
25. Code of Federal Regulations. Title 40 part 53.22, July 1976.
26. Butcher, S.S. and R.E. Ruff. Effect of Inlet Residence Time on Analysis of Atmospheric Nitrogen Oxides and Ozone, Anal. Chem., 43:1890, 1971.
27. Slowik, A.A. and E.B. Sansone. Diffusion Losses of Sulfur Dioxide in Sampling Manifolds. J. Air. Poll. Con. Assoc., 24:245, 1974.
28. Yamada, V.M. and R.J. Charlson. Proper Sizing of the Sampling Inlet Line for a Continuous Air Monitoring Station. Environ. Sci. and Technol., 3:483, 1969.
29. Koch, R.C. and H.E. Rector. Optimum Network Design and Site Exposure Criteria for Particulate Matter, GEOMET Technologies, Inc., Rockville, MD. Prepared for U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA Contract No. 68-02-3584. EPA 450/4-87-009. May 1987.
30. Burton, R.M. and J.C. Suggs. Philadelphia Roadway Study. Environmental Monitoring Systems Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, N.C. EPA-600/4-84-070 September 1984.
31. Technical Assistance Document For Sampling and Analysis of Ozone Precursors. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/8-91-215. October 1991.
32. Quality Assurance Handbook for Air Pollution Measurement Systems: Volume IV. Meteorological Measurements. Atmospheric Research and Exposure Assessment Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 600/4-90-0003. August 1989.
33. On-Site Meteorological Program Guidance for Regulatory Modeling Applications. Office of Air Quality Planning and Standards, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711. EPA 450/4-87-013. June 1987F. [71 FR 61323, Oct. 17, 2006, as amended at 75 FR 6535, Feb. 9, 2010; 76 FR 54342, Aug. 31, 2011; 78 FR 3285, Jan. 15, 2013]
Sec. Appendix F to Part 58 [Reserved]
Sec. Appendix G to Part 58--Uniform Air Quality Index (AQI) and Daily
Reporting
General Requirements
1. What is the AQI?
2. Why report the AQI?
3. Must I report the AQI?
4. What goes into my AQI report?
5. Is my AQI report for my MSA only?
6. How do I get my AQI report to the public?
7. How often must I report the AQI?
8. May I make exceptions to these reporting requirements?
Calculation
9. How Does the AQI Relate to Air Pollution Levels?
10. What Monitors Should I Use To Get the Pollutant Concentrations for Calculating the AQI?
11. Do I have to forecast the AQI?
12. How Do I Calculate the AQI?
Background and Reference Materials
13. What Additional Information Should I Know?
General Requirements
1. What Is the AQI?
The AQI is a tool that simplifies reporting air quality to the general public. The AQI incorporates into a single index concentrations of 5 criteria pollutants: ozone (O3), particulate matter (PM), carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen dioxide (NO2). The scale of the index is divided into general categories that are associated with health messages.
2. Why Report the AQI?
The AQI offers various advantages:
a. It is simple to create and understand.
b. It conveys the health implications of air quality.
c. It promotes uniform use throughout the country.
3. Must I Report the AQI?
You must report the AQI daily if yours is a metropolitan statistical area (MSA) with a population over 350,000.
4. What Goes Into My AQI Report?
i. Your AQI report must contain the following:
a. The reporting area(s) (the MSA or subdivision of the MSA).
b. The reporting period (the day for which the AQI is reported).
c. The critical pollutant (the pollutant with the highest index value).
d. The AQI (the highest index value).
e. The category descriptor and index value associated with the AQI and, if you choose to report in a color format, the associated color. Use only the following descriptors and colors for the six AQI categories:
Table 1--AQI Categories------------------------------------------------------------------------
And this color
For this AQI Use this descriptor \1\------------------------------------------------------------------------0 to 50.......................... ``Good''............ Green.------------------------------------------------------------------------51 to 100........................ ``Moderate''........ Yellow.------------------------------------------------------------------------101 to 150....................... ``Unhealthy for Orange.
Sensitive Groups''.------------------------------------------------------------------------151 to 200....................... ``Unhealthy''....... Red.------------------------------------------------------------------------201 to 300....................... ``Very Unhealthy''.. Purple.------------------------------------------------------------------------301 and above.................... ``Hazardous''....... Maroon.\1\------------------------------------------------------------------------\1\ Specific colors can be found in the most recent reporting guidance
(Guideline for Public Reporting of Daily Air Quality--Air Quality
Index (AQI)).
f. The pollutant specific sensitive groups for any reported index value greater than 100. Use the following sensitive groups for each pollutant: ------------------------------------------------------------------------
When this pollutant has an index value Report these sensitive groups
above 100 * * * * * *------------------------------------------------------------------------Ozone................................... Children and people with
asthma are the groups most at
risk.------------------------------------------------------------------------PM 2.5.................................. People with respiratory or
heart disease, the elderly
and children are the groups
most at risk.------------------------------------------------------------------------PM 10................................... People with respiratory
disease are the group most at
risk.------------------------------------------------------------------------CO...................................... People with heart disease are
the group most at risk.------------------------------------------------------------------------SO2..................................... People with asthma are the
group most at risk.------------------------------------------------------------------------NO2..................................... Children and people with
respiratory disease are the
groups most at risk.------------------------------------------------------------------------
ii. When appropriate, your AQI report may also contain the following:
a. Appropriate health and cautionary statements.
b. The name and index value for other pollutants, particularly those with an index value greater than 100.
c. The index values for sub-areas of your MSA.
d. Causes for unusual AQI values.
e. Actual pollutant concentrations.
5. Is My AQI Report for My MSA Only?
Generally, your AQI report applies to your MSA only. However, if a significant air quality problem exists (AQI greater than 100) in areas significantly impacted by your MSA but not in it (for example, O3 concentrations are often highest downwind and outside an urban area), you should identify these areas and report the AQI for these areas as well.
6. How Do I Get My AQI Report to the Public?
You must furnish the daily report to the appropriate news media (radio, television, and newspapers). You must make the daily report publicly available at one or more places of public access, or by any other means, including a recorded phone message, a public Internet site, or facsimile transmission. When the AQI value is greater than 100, it is particularly critical that the reporting to the various news media be as extensive as possible. At a minimum, it should include notification to the media with the largest market coverages for the area in question.
7. How Often Must I Report the AQI?
You must report the AQI at least 5 days per week. Exceptions to this requirement are in section 8 of this appendix.
8. May I Make Exceptions to These Reporting Requirements?
i. If the index value for a particular pollutant remains below 50 for a season or year, then you may exclude the pollutant from your calculation of the AQI in section 12.
ii. If all index values remain below 50 for a year, then you may report the AQI at your discretion. In subsequent years, if pollutant levels rise to where the AQI would be above 50, then the AQI must be reported as required in sections 3, 4, 6, and 7 of this appendix.
Calculation
9. How does the AQI relate to air pollution levels?
For each pollutant, the AQI transforms ambient concentrations to a scale from 0 to 500. The AQI is keyed as appropriate to the national ambient air quality standards (NAAQS) for each pollutant. In most cases, the index value of 100 is associated with the numerical level of the short-term standard (i.e., averaging time of 24-hours or less) for each pollutant. The index value of 50 is associated with the numerical level of the annual standard for a pollutant, if there is one, at one-half the level of the short-term standard for the pollutant, or at the level at which it is appropriate to begin to provide guidance on cautionary language. Higher categories of the index are based on increasingly serious health effects and increasing proportions of the population that are likely to be affected. The index is related to other air pollution concentrations through linear interpolation based on these levels. The AQI is equal to the highest of the numbers corresponding to each pollutant. For the purposes of reporting the AQI, the sub-indexes for PM 10 and PM 2.5 are to be considered separately. The pollutant responsible for the highest index value (the reported AQI) is called the ``critical'' pollutant.
10. What monitors should I use to get the pollutant concentrations for
calculating the AQI?
You must use concentration data from State/Local Air Monitoring Station (SLAMS) or parts of the SLAMS required by 40 CFR 58.10 for each pollutant except PM. For PM, calculate and report the AQI on days for which you have measured air quality data (e.g., from continuous PM 2.5 monitors required in Appendix D to this part). You may use PM measurements from monitors that are not reference or equivalent methods (for example, continuous PM 10 or PM 2.5 monitors). Detailed guidance for relating non-approved measurements to approved methods by statistical linear regression is referenced in section 13 below.
11. Do I Have to Forecast the AQI?
You should forecast the AQI to provide timely air quality information to the public, but this is not required. If you choose to forecast the AQI, then you may consider both long-term and short-term forecasts. You can forecast the AQI at least 24-hours in advance using the most accurate and reasonable procedures considering meteorology, topography, availability of data, and forecasting expertise. The document ``Guideline for Developing an Ozone Forecasting Program'' (the Forecasting Guidance) will help you start a forecasting program. You can also issue short-term forecasts by predicting 8-hour ozone values from 1-hour ozone values using methods suggested in the Reporting Guidance, ``Guideline for Public Reporting of Daily Air Quality.''
12. How do I calculate the AQI?
i. The AQI is the highest value calculated for each pollutant as follows:
a. Identify the highest concentration among all of the monitors within each reporting area and truncate as follows: (1) Ozone--truncate to 3 decimal placesPM 2.5--truncate to 1 decimal placePM 10--truncate to integer CO--truncate to 1 decimal placeSO2--truncate to integerNO2--truncate to integer
(2) [Reserved]
b. Using Table 2, find the two breakpoints that contain the concentration.
c. Using Equation 1, calculate the index.
d. Round the index to the nearest integer.
Table 2--Breakpoints for the AQI--------------------------------------------------------------------------------------------------------------------------------------------------------
These breakpoints Equal these AQI's--------------------------------------------------------------------------------------------------------------------------------------------------------
PM 2.5 (g/m\3\) 24- m>g/m\3\) 24- CO (ppm) SO2 (ppb) NO2 (ppb) AQI Category
hour\1\ hour hour 8-hour 1-hour 1-hour--------------------------------------------------------------------------------------------------------------------------------------------------------0.000-0.059........................ ........... 0.0-12.0 0-54 0.0-4.4 0-35 0-53 0-50 Good.0.060-0.075........................ ........... 12.1-35.4 55-154 4.5-9.4 36-75 54-100 51-100 Moderate.0.076-0.095........................ 0.125-0.164 35.5-55.4 155-254 9.5-12.4 76-185 101-360 101-150 Unhealthy for
Sensitive Groups.0.096-0.115........................ 0.165-0.204 \3\ 55.5-150.4 255-354 12.5-15.4 \4\ 186- 361-649 151-200 Unhealthy.
3040.116-0.374........................ 0.205-0.404 \3\ 150.5-250.4 355-424 15.5-30.4 \4\ 305- 650-1249 201-300 Very Unhealthy.
604(\2\).............................. 0.405-0.504 \3\ 250.5-350.4 425-504 30.5-40.4 \4\ 605- 1250-1649 301-400 Hazardous.
804(\2\).............................. 0.505-0.604 \3\ 350.5-500.4 505-604 40.5-50.4 \4\ 805- 1650-2049 401-500
1004--------------------------------------------------------------------------------------------------------------------------------------------------------\1\ Areas are generally required to report the AQI based on 8-hour ozone values. However, there are a small number of areas where an AQI based on 1-hour
ozone values would be more precautionary. In these cases, in addition to calculating the 8-hour ozone index value, the 1-hour ozone index value may be
calculated, and the maximum of the two values reported.\2\ 8-hour O\3\ values do not define higher AQI values ("301). AQI values of 301 or greater are calculated with 1-hour O3 concentrations.\3\ If a different SHL for PM 2.5 is promulgated, these numbers will change accordingly.\4\ 1-hr SO2 values do not define higher AQI values ("200). AQI values of 200 or greater are calculated with 24-hour SO2 concentrations.
ii. If the concentration is equal to a breakpoint, then the index is equal to the corresponding index value in Table 2. However, Equation 1 can still be used. The results will be equal. If the concentration is between two breakpoints, then calculate the index of that pollutant with Equation 1. You must also note that in some areas, the AQI based on 1-hour O3 will be more precautionary than using 8-hour values (see footnote 1 to Table 2). In these cases, you may use 1-hour values as well as 8-hour values to calculate index values and then use the maximum index value as the AQI for O3.[GRAPHIC] [TIFF OMITTED] TR27MR08.001 Where: Ip = the index value for pollutantpCp = the truncated concentration of pollutantpBPHi = the breakpoint that is greater than or equal to
CpBPLo = the breakpoint that is less than or equal to
CpIHi = the AQI value corresponding to BPHiIlo = the AQI value corresponding to BPLo.
iii. If the concentration is larger than the highest breakpoint in Table 2 then you may use the last two breakpoints in Table 2 when you apply Equation 1.
Example
iv. Using Table 2 and Equation 1, calculate the index value for each of the pollutants measured and select the one that produces the highest index value for the AQI. For example, if you observe a PM 10 value of 210 g/m\3\, a 1-hour O3 value of 0.156 ppm, and an 8-hour O3 value of 0.130 ppm, then do this:
a. Find the breakpoints for PM 10 at 210 g/m\3\ as 155 g/m\3\ and 254 g/m\3\, corresponding to index values 101 and 150;
b. Find the breakpoints for 1-hour O3 at 0.156 ppm as 0.125 ppm and 0.164 ppm, corresponding to index values 101 and 150;
c. Find the breakpoints for 8-hour O3 at 0.130 ppm as 0.116 ppm and 0.374 ppm, corresponding to index values 201 and 300;
d. Apply Equation 1 for 210 g/m\3\, PM 10:
[GRAPHIC] [TIFF OMITTED] TR27MR08.002
e. Apply Equation 1 for 0.156 ppm, 1-hour O3: [GRAPHIC] [TIFF OMITTED] TR27MR08.003
f. Apply Equation 1 for 0.130 ppm, 8-hour O3:
[GRAPHIC] [TIFF OMITTED] TR27MR08.004
g. Find the maximum, 206. This is the AQI. The minimal AQI report would read:
v. Today, the AQI for my city is 206 which is Very Unhealthy, due to ozone. Children and people with asthma are the groups most at risk.
13. What additional information should I know?
The EPA has developed a computer program to calculate the AQI for you. The program prompts for inputs, and it displays all the pertinent information for the AQI (the index value, color, category, sensitive group, health effects, and cautionary language). The EPA has also prepared a brochure on the AQI that explains the index in detail (The Air Quality Index), Reporting Guidance (Technical Assistance Document for the Reporting of Daily Air Quality--the Air Quality Index (AQI)) that provides associated health effects and cautionary statements, and Forecasting Guidance (Guideline for Developing an Ozone Forecasting Program) that explains the steps necessary to start an air pollution forecasting program. You can download the program and the guidance documents at www.airnow.gov. Reference for relating non-approved PM measurements to approved methods (Eberly, S., T. Fitz-Simons, T. Hanley, L. Weinstock., T. Tamanini, G. Denniston, B. Lambeth, E. Michel, S. Bortnick. Data Quality Objectives (DQOs) For Relating Federal Reference Method (FRM) and Continuous PM 2.5 Measurements to Report an Air Quality Index (AQI). U.S. Environmental Protection Agency, Research Triangle Park, NC. EPA-454/B-02-002, November 2002) can be found on the Ambient Monitoring Technology Information Center (AMTIC) Web site, http://www.epa.gov/ttnamti1/. [64 FR 42547, Aug. 4, 1999, as amended at 73 FR 16513, Mar. 27, 2008; 75 FR 6537, Feb. 9, 2010; 75 FR 35602, June 22, 2010; 78 FR 3286, Jan. 15, 2013]