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 Culberson County, Texas, and

Dallam County, Texas, give the percentage contributions from specific air pollution sources.  The Culberson County Seat is Van Horn, Texas, and the Dallam County Seat is Dalhart, Texas.