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 Lake County, Minnesota, and

Lake of the Woods County, Minnesota, give the percentage contributions from specific air pollution sources.  The Lake County Seat is Two Harbors, Minnesota, and the Lake of the Woods County Seat is Baudette, Minnesota.