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 Renville County, North Dakota, and

Richland County, North Dakota, give the percentage contributions from specific air pollution sources.  The Renville County Seat is Mohall, North Dakota, and the Richland County Seat is Wahpeton, North Dakota.