CFR > Title 40 - Protection of Environment > CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY > SUBCHAPTER C—AIR PROGRAMS (Parts 50–99) > PART 52—APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS > SUBPART LL—Oklahoma (§52.1920 to §52.1960) > 52.1921—Classification of regions.

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

Code of Federal Regulations

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