52.1421—Classification of regions.
The Nebraska 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 Omaha-Council Bluffs Interstate | I | II | III | III | III |
| Lincoln-Beatrice-Fairbury Intrastate | II | III | III | III | III |
| Metropolitan Sioux City Interstate | III | III | III | III | III |
| Nebraska Intrastate | III | III | III | III | III |