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 Eaton County, Michigan, and

Emmet County, Michigan, give the percentage contributions from specific air pollution sources.  The Eaton County Seat is Charlotte, Michigan, and the Emmet County Seat is Petoskey, Michigan.