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 Anoka County, Minnesota, and

Becker County, Minnesota, give the percentage contributions from specific air pollution sources.  The Anoka County Seat is Anoka, Minnesota, and the Becker County Seat is Detroit Lakes, Minnesota.