52.1321—Classification of regions.
The Missouri plans were 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 Kansas City Interstate | I | III | III | I | I |
| Southwest Missouri Intrastate | I | III | III | III | III |
| Southeast Missouri Intrastate | III | III | III | III | III |
| Northern Missouri Intrastate | II | III | III | III | III |
| Metropolitan St. Louis Interstate | I | I | III | I | I |