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 Grundy County, Iowa, and

Guthrie County, Iowa, give the percentage contributions from specific air pollution sources.  The Grundy County Seat is Grundy Center, Iowa, and the Guthrie County Seat is Guthrie Center, Iowa.