Abstract: The Environmental Protection Agency (EPA) compiles data on emission tonnages of air pollutants for US counties.  US Air Quality Gradebook ("AirGrades") source sheets give the percentage contributions from specific air pollution sources.  This source sheet is for

Beaverhead County, Montana; Big Horn County, Montana; and Blaine County, Montana.  The Beaverhead County Seat is Dillon, Montana; the Big Horn County Seat is Hardin, Montana; and the Blaine County Seat is Chinook, Montana.