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 Barron County, Wisconsin, and

Bayfield County, Wisconsin, give the percentage contributions from specific air pollution sources.  The Barron County Seat is Barron, Wisconsin, and the Bayfield County Seat is Washburn, Wisconsin.