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 Catahoula Parish, Louisiana, and

Claiborne Parish, Louisiana, give the percentage contributions from specific air pollution sources.  The Catahoula Parish Seat is Harrisonburg, Louisiana, and the Claiborne Parish Seat is Homer, Louisiana.