U.S. Code of Federal Regulations

Regulations most recently checked for updates: Aug 27, 2025

§ 52.921 - Classification of regions.

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

Air quality control region Pollutant
Particulate matter Sulfur oxides Nitrogen dioxide Carbon monoxide Photochemical oxidants (hydrocarbons)
Appalachian IntrastateIIIIIIIIIIIIII
Bluegrass IntrastateIIIIIIIIIIIIII
Evansville (Indiana)-Owensboro-Henderson (Kentucky) InterstateIIIIIIIIIIII
Huntington (West Virginia)-Ashland (Kentucky)-Portsmouth-Ironton (Ohio) InterstateIIIIIIIIIIIII
Louisville InterstateIIIIIIIII
Metropolitan Cincinnati InterstateIIIIIIIIII
North Central Kentucky IntrastateIIIIIIIIIIIIII
Paducah (Kentucky)-Cairo (Illinois) InterstateIIIIIIIIIIII
South Central Kentucky IntrastateIIIIIIIIIIIIIII
[37 FR 10868, May 31, 1972, as amended at 39 FR 16346, May 8, 1974]