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

Missoula County, Montana; Musselshell County, Montana; and Park County, Montana.  The Missoula County Seat is Missoula, Montana; the Musselshell County Seat is Roundup, Montana; and the Park County Seat is Livingston, Montana.