The Oregon plan was evaluated on the basis of the following classifications: ----------------------------------------------------------------------------------------------------------------
Pollutant
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Air quality control region Particulate Sulfur Nitrogen Carbon
matter oxides dioxide monoxide Ozone----------------------------------------------------------------------------------------------------------------Portland Interstate....................................... I IA III I ISouthwest Oregon Intrastate............................... II III III III IIINorthwest Oregon Intrastate............................... III III III III IIICentral Oregon Intrastate................................. II III III III IIIEastern Oregon Intrastate................................. II III III III III---------------------------------------------------------------------------------------------------------------- [37 FR 10888, May 31, 1972, as amended at 45 FR 42278, June 24, 1980]