52.1221—Classification of regions.

The Minnesota plan was evaluated on the basis of the following classifications:

Air quality control region	Pollutant
Air quality control region	Particulate matter	Sulfur oxides	Nitrogen dioxide	Carbon monoxide	Photochemical oxidants (hydrocarbons)
Central Minnesota Intrastate	II	III	III	III	III
Southeast Minnesota-La Crosse (Wisconsin) Interstate	II	Ia	III	III	III
Duluth (Minnesota)-Superior (Wisconsin) Interstate	I	II	III	III	III
Metropolitan Fargo-Moorhead Interstate	II	III	III	III	III
Minneapolis-St. Paul Intrastate	I	I	III	I	III
Northwest Minnesota Intrastate	II	III	III	III	III
Southwest Minnesota Intrastate	III	III	III	III	III

Code of Federal Regulations

[37 FR 10874, May 31, 1972, as amended at 39 FR 16346, May 8, 1974]