The Iowa plan was evaluated on the basis of the following classification:
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 |
Metropolitan Sioux Falls Interstate | II | III | III | III | III |
Metropolitan Sioux City Interstate | III | III | III | III | III |
Metropolitan Dubuque Interstate | I | III | III | III | III |
Metropolitan Quad Cities Interstate | I | III | III | III | III |
Burlington-Keokuk Interstate | I | I | III | III | III |
Northwest Iowa Intrastate | III | III | III | III | III |
North Central Iowa Intrastate | IA | III | III | III | III |
Northeast Iowa Intrastate | I | III | III | III | III |
Southwest Iowa Intrastate | III | III | III | III | III |
South Central Iowa Intrastate | I | III | III | III | I |
Southeast Iowa Intrastate | III | III | III | III | III |
40 C.F.R. §52.821