The Minnesota plan was evaluated on the basis of the following classifications: ----------------------------------------------------------------------------------------------------------------
Pollutant
----------------------------------------------------------
Air quality control region Photochemical
Particulate Sulfur Nitrogen Carbon oxidants
matter oxides dioxide monoxide (hydrocarbons)----------------------------------------------------------------------------------------------------------------Central Minnesota Intrastate......................... II III III III IIISoutheast Minnesota-La Crosse (Wisconsin) Interstate. II Ia III III IIIDuluth (Minnesota)-Superior (Wisconsin) Interstate... I II III III IIIMetropolitan Fargo-Moorhead Interstate............... II III III III IIIMinneapolis-St. Paul Intrastate...................... I I III I IIINorthwest Minnesota Intrastate....................... II III III III IIISouthwest Minnesota Intrastate....................... III III III III III---------------------------------------------------------------------------------------------------------------- [37 FR 10874, May 31, 1972, as amended at 39 FR 16346, May 8, 1974]