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

Starr County, Texas; Stephens County, Texas; and Sterling County, Texas.  The Starr County Seat is Rio Grande City, Texas; the Stephens County Seat is Breckenridge, Texas; and the Sterling County Seat is Sterling City, Texas.