Abstract: The Environmental Protection Agency (EPA) compiles data on emission tonnages of air pollutants for US counties.  US Air Quality Gradebook ("AirGrades") source sheets such as this one for Barbour County, Alabama, and

Bibb County, Alabama, give the percentage contributions from specific air pollution sources.  The Barbour County Seat is Clayton, Alabama, and the Bibb County Seat is Centreville, Alabama.