40 CFR 52.671 - Classification of regions.

Regulations most recently checked for updates: Aug 27, 2025

§ 52.671 - Classification of regions.

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

Air quality control region	Pollutants
Air quality control region	Particulate matter	Sulfur oxides	Nitrogen dioxide	Carbon monoxide	Ozone
Eastern Idaho Intrastate	I	II	III	III	III.
Eastern Washington Northern Idaho Interstate (Idaho)	I	II	III	III	III.
Idaho Intrastate	I	III	III	III	III.
Metropolitan Boise Intrastate	II	III	III	I	III.

[37 FR 10861, May 31, 1972, as amended at 45 FR 70261, Oct. 23, 1980; 47 FR 32534, July 28, 1982]