C.F.R. » Title 40 » CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY › SUBCHAPTER C—AIR PROGRAMS › PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS › Subpart J—District of Columbia

40 C.F.R. § 52.471

Classification of regions

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The District of Columbia plan was evaluated on the basis of the following classifications:

Air quality control regionPollutant
Particulate matterSulfur oxidesNitrogen dioxideCarbon monoxideOzone
National Capital InterstateIIIIIII
[37 FR 10857, May 31, 1972, as amended at 39 FR 16346, May 8, 1974; 46 FR 61263, Dec. 16, 1981]