Classification of regions.

The Maryland plans were evaluated on the basis of the following classifications: Air quality control region Pollutant Particulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Ozone Cumberland-Keyser Interstate I I III III III Central Maryland Intrastate II II III III III Metropolitan Baltimore Intrastate I I I I I National Capital Interstate I I III I I Southern Maryland Intrastate III III III III III Eastern Shore Intrastate II III III III III [37 FR 10870, May 31, 1972, as amended at 39 FR 16346, May 8, 1974; 45 FR 53475, Aug. 12, 1980]