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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 Oklahoma
  air quality by county. 
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   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. 
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