40 C.F.R. § 52.421
Classification of regions
The Delaware 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) | |
| Metropolitan Philadelphia Interstate | I | I | III | I | I |
| Southern Delaware Intrastate | III | III | III | III | III |