(a) Pursuant to section 172(a)(2)(C)(ii) of the Act, a State with an area that fails to attain the PM2.5 NAAQS by its attainment date may apply for an initial 1-year attainment date extension if the State has complied with all requirements and commitments pertaining to the area in the applicable implementation plan, and:
(1) For an area that violates the annual PM2.5 NAAQS as of its attainment date, the annual average concentration for the most recent year at each monitor is 15.0 [micro]g/m\3\ or less (calculated according to the data analysis requirements in 40 CFR part 50, appendix N).
(2) For an area that violates the 24-hour PM2.5 NAAQS as of its attainment date, the 98th percentile concentration for the most recent year at each monitor is 65 [micro]g/m\3\ or less (calculated according to the data analysis requirements in 40 CFR part 50, appendix N).
(b) An area that fails to attain the PM2.5 NAAQS after receiving a 1-year attainment date extension may apply for a second 1-year attainment date extension pursuant to section 172(a)(2)(C)(ii) if the State has complied with all requirements and commitments pertaining to the area in the applicable implementation plan, and:
(1) For an area that violates the annual PM2.5 NAAQS as of its attainment date, the two-year average of annual average concentrations at each monitor, based on the first extension year and the previous year, is 15.0 [micro]g/m\3\ or less (calculated according to the data analysis requirements in 40 CFR part 50, appendix N).
(2) For an area that violates the 24-hour PM2.5 NAAQS as of its attainment date, the two-year average of annual 98th percentile concentrations at each monitor, based on the first extension year and the previous year, is 65 [micro]g/m\3\ or less (calculated according to the data analysis requirements in 40 CFR part 50, appendix N).