40 C.F.R. § 52.51
Classification of regions
The Alabama plan was evaluated on the basis of the following classifications:
| Air quality control region | Pollutant | ||||
|---|---|---|---|---|---|
| Particulate matter | Sulfur oxides | Nitrogen dioxide | Carbon monoxide | Photochemical oxidants (hydrocarbons) | |
| Alabama & Tombigbee Rivers Intrastate | II | III | III | III | III |
| Columbus (Georgia)-Phenix City (Alabama) Interstate | I | III | III | III | III |
| East Alabama Intrastate | I | III | III | III | III |
| Metropolitan Birmingham Intrastate | I | II | III | I | I |
| Mobile (Alabama)-Pensacola-Panama City (Florida)-Southern Mississippi Interstate | I | I | III | III | I |
| Southeast Alabama Intrastate | II | III | III | III | III |
| Tennessee River Valley (Alabama)-Cumberland Mountains (Tennessee) Interstate | I | I | III | III | III |