California Air Quality
California Air Quality Map

Grade A Color: Blue

 A    

Grade B Color: Cyan

 B    

Grade C Color: Green

 C    

Grade D Color: Yellow

 D    

Grade F Color: Red

 F

A = Best/Cleanest in the US; F = Worst/Dirtiest in the US.

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Abstract: US Air Quality Gradebook ("AirGrades") maps present a visual picture of air quality for more than 3,000 US counties.  This map shows California air quality by county.

Grades are based on air pollution data from the Environmental Protection Agency (EPA) for 10 measures of ambient pollutant concentrations and for emission tonnages of 11 air pollutants.