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 Crockett County, Texas, and

Crosby County, Texas, give the percentage contributions from specific air pollution sources.  The Crockett County Seat is Ozona, Texas, and the Crosby County Seat is Crosbyton, Texas.