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 Chowan County, North Carolina, and

Clay County, North Carolina, give the percentage contributions from specific air pollution sources.  The Chowan County Seat is Edenton, North Carolina, and the Clay County Seat is Hayesville, North Carolina.