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 Mellette County, South Dakota, and

Miner County, South Dakota, give the percentage contributions from specific air pollution sources.  The Mellette County Seat is White River, South Dakota, and the Miner County Seat is Howard, South Dakota.