40 CFR 52.1921 - Classification of regions.

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

Air quality control region	Pollutant					Particulate matter	Sulfur oxides	Nitrogen dioxide	Carbon monoxide	Ozone	Central Oklahoma Intrastate	I	III	III	III	I	Northeastern Oklahoma Intrastate	I	III	III	III	I	Southeastern Oklahoma Intrastate	III	III	III	III	III	North Central Oklahoma Intrastate	III	III	III	III	III	Southwestern Oklahoma Intrastate	III	III	III	III	III	Northwestern Oklahoma Intrastate	III	III	III	III	III	Metropolitan Fort Smith Interstate	II	III	III	III	III	Shreveport-Texarkana-Tyler Interstate	II	III	III	III	III

[37 FR 10887, May 31, 1972, as amended at 45 FR 9741, Feb. 13, 1980]