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 Benton County, Minnesota, and

Big Stone County, Minnesota, give the percentage contributions from specific air pollution sources.  The Benton County Seat is Foley, Minnesota, and the Big Stone County Seat is Ortonville, Minnesota.