40 CFR § 52.471
Classification of regions
June 9, 2020
The District of Columbia plan was evaluated on the basis of the following classifications:
Open Table
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]