The District of Columbia plan was evaluated on the basis of the following classifications: ----------------------------------------------------------------------------------------------------------------
Pollutant
-----------------------------------------------------
Air quality control region Particulate Sulfur Nitrogen Carbon
matter oxides dioxide 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]