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 Tehama County, California, and

Trinity County, California, give the percentage contributions from specific air pollution sources.  The Tehama County Seat is Red Bluff, California, and the Trinity County Seat is Weaverville, California.