40 CFR § 52.471 - Classification of regions.

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

Air quality control region	Pollutant
	Particulate matter	Sulfur oxides	Nitrogen dioxide	Carbon monoxide	Ozone
National Capital Interstate	I	I	III	I	I

[37 FR 10857, May 31, 1972, as amended at 39 FR 16346, May 8, 1974; 46 FR 61263, Dec. 16, 1981]