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 Arenac County, Michigan, and

Baraga County, Michigan, give the percentage contributions from specific air pollution sources.  The Arenac County Seat is Standish, Michigan, and the Baraga County Seat is L'Anse, Michigan.