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 Union County, Iowa, and

Van Buren County, Iowa, give the percentage contributions from specific air pollution sources.  The Union County Seat is Creston, Iowa, and the Van Buren County Seat is Keosauqua, Iowa.