40 CFR 52.821 - Classification of regions.

Regulations last checked for updates: Dec 17, 2025

Title 40 - Protection of Environment last revised: Nov 17, 2028

§ 52.821 - Classification of regions.

The Iowa plan was evaluated on the basis of the following classification:

Air quality control region	Pollutant
Air quality control region	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

[37 FR 10865, May 31, 1972, as amended at 39 FR 16346, May 8, 1974]

authority: 42 U.S.C. 7401

cite as: 40 CFR 52.821