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 Choctaw County, Oklahoma, and

Cimarron County, Oklahoma, give the percentage contributions from specific air pollution sources.  The Choctaw County Seat is Hugo, Oklahoma, and the Cimarron County Seat is Boise City, Oklahoma.