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4th Maximum Ozone Values Table (ppb) through September 30, 2010

Click here to view the updated table.

The ozone standard set by the U.S. Environmental Protection Agency (EPA) is calculated using a rolling three-year average of the fourth (4th) maximum 8-hour ozone concentrations. An official violation occurs when the rolling three-year average meets or exceeds 75 parts per billion (ppb), a standard set in 2008. The table above shows current monitoring data for the Denver metropolitan region including 1st, 2nd, 3rd and 4th maximum values as well as data for 2008 and 2009 to calculate the average for three years. The region is currently designated as a “non-attainment” region by the U.S. EPA. A new, stricter ozone standard is expected in August 2010.

The Voluntary Ozone Reduction Program began in 1999 in response to unusually high ozone levels in the summer of 1998. The RAQC’s ozone education campaign – “Let’s Take Care of Our Summer Air” – includes issuance of Ozone Action Alerts, advertising and community events. In addition, the RAQC posts information on the campaign and asks citizens to Join Our Clean Air Community on the Pledge page of the web site.

For additional information on ground-level ozone, please visit the “What is Ground-level ozone?” page on the site or the RAQC’s Web site at http://www.raqc.org or call (303) 629-5450, ext. 220.