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 Richland Parish, Louisiana, and

Sabine Parish, Louisiana, give the percentage contributions from specific air pollution sources.  The Richland Parish Seat is Rayville, Louisiana, and the Sabine Parish Seat is Many, Louisiana.