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 |