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 Horry County, South Carolina, and

Jasper County, South Carolina, give the percentage contributions from specific air pollution sources.  The Horry County Seat is Conway, South Carolina, and the Jasper County Seat is Ridgeland, South Carolina.