52.2571—Classification of regions.
The Wisconsin plan was evaluated on the basis of the following classifications:
| Air quality control region | Pollutant | ||||
|---|---|---|---|---|---|
| Particulate matter | Sulfur oxides | Nitrogen dioxide | Carbon monoxide | Ozone | |
| Duluth (Minnesota)-Superior (Wisconsin) Interstate | I | II | III | III | III |
| North Central Wisconsin Intrastate | II | III | III | III | III |
| Lake Michigan Intrastate | II | III | III | III | III |
| Southeast Minnesota-La Crosse (Wisconsin) Interstate | II | IA | III | III | III |
| Southern Wisconsin Intrastate | II | III | III | III | III |
| Southeastern Wisconsin Intrastate | I | II | III | III | I |
| Rockford (Illinois)-Jamesville-Beloit (Wisconsin) Interstate | II | III | III | III | III |
| Metropolitan Dubuque Interstate | I | III | III | III | III |