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 Cambria County, Pennsylvania, and

Cameron County, Pennsylvania, give the percentage contributions from specific air pollution sources.  The Cambria County Seat is Ebensburg, Pennsylvania, and the Cameron County Seat is Emporium, Pennsylvania.