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 Orange County, North Carolina, and

Pamlico County, North Carolina, give the percentage contributions from specific air pollution sources.  The Orange County Seat is Hillsborough, North Carolina, and the Pamlico County Seat is Bayboro, North Carolina.