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 Trempealeau County, Wisconsin, and

Vernon County, Wisconsin, give the percentage contributions from specific air pollution sources.  The Trempealeau County Seat is Whitehall, Wisconsin, and the Vernon County Seat is Viroqua, Wisconsin.