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

Holt County, Nebraska; Hooker County, Nebraska; and Howard County, Nebraska.  The Holt County Seat is O'Neill, Nebraska; the Hooker County Seat is Mullen, Nebraska; and the Howard County Seat is Saint Paul, Nebraska.