California Air Quality
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.