Historical Archive
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July 2009
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This historical data calendar search is based on the latest National Ambient Air Quality Standards as established by U.S. EPA: ground-level ozone standard of .075 parts per million averaged over 8 hours; and PM 2.5 standard of 35 micrograms per cubic meter of air over a 24-hour period.

Historical data prior to January 2008 is not searchable, but is instead featured in monthly images from 2002-2007. This data is based on the previous National Ambient Air Quality Standards of .084 parts per million averaged over 8 hours for ozone and 65 micrograms per cubic meter of air over 24 hours for PM 2.5, which were the standards in effect at that time.

View 2002-2007 historical air quality