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Air Trends
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Air Quality Trends - How to Interpret the Graphs

The blue band shows the distribution of air pollution levels among the trend sites, displaying the middle 80 percent. The white line represent the average among all the trend sites. Ninety percent of sites have concentrations below the top line, while ten percent of sites have concentrations below the bottom line. 

Example graph to explain the trend graphs for the pollutants

For each pollutant, the trend statistic is directly related to the level and averaging time of the National Ambient Air Quality Standard (NAAQS). For more information regarding the levels and averaging times for the NAAQS statistics, see the NAAQS Table.

  • Air Trends Home
  • Air Quality - National Summary
  • Air Quality - Cities and Counties
  • Air Quality Design Values
  • Previous Air Quality Trends Reports
  • Carbon Monoxide Trends
  • Lead Trends
  • Nitrogen Dioxide Trends
  • Ozone Trends
  • Particulate Matter (PM10) Trends
  • Particulate Matter (PM2.5) Trends
  • Sulfur Dioxide Trends
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on May 3, 2022
United States Environmental Protection Agency

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