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 Humphreys County, Mississippi, and

Issaquena County, Mississippi, give the percentage contributions from specific air pollution sources.  The Humphreys County Seat is Belzoni, Mississippi, and the Issaquena County Seat is Mayersville, Mississippi.