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	The Regional Air Quality Council (RAQC) is spearheading metro Denver's campaign to help curb ozone pollution in order to promote public health, to maintain air quality, and to head off possible consequences of non-compliance with the U.S. Environmental Protection Agency's (EPA) new, stricter 8-hour ozone standard.

8-Hour Ozone Standard

In 1997, EPA established a new 8-hour standard of 80 parts per billion (ppb) to replace the previous 1-hour ozone standard. Under the new standard, a violation occurs if the three-year average of the fourth highest recorded levels at any one particular monitor is greater than or equal to 85 ppb.

During the 2003 ozone season (June 1 - August 31), three metro-area monitors recorded values high enough to push the three-year average over the new standard.  NREL monitor's three year average is 76 ppb.  Chatfield is at 78 ppb and Rocky Flats is at 79 ppb.  Please see the table below for values at the rest of the metro-area monitors or refer to the 2003 Voluntary Ozone Reduction Program Summary.  

U.S. Supreme Court Upholds New Ozone and PM2.5 Standards

In a landmark decision issued on February 27, 2001, the U.S. Supreme Court unanimously upheld EPA's authority and process for establishing new health-based standards for ozone and PM2.5.  The decision was in response to a 1999 U.S. Court of Appeals decision that overturned these standards in response to a lawsuit filed by the American Trucking Association et al.

The Supreme Court ruled that the Clean Air Act does not give the EPA lawmaking power in its standard-setting function, as the Court of Appeals had determined.  Instead, the Supreme Court determined EPA exercised its authority properly under the Clean Air Act in establishing the standards.

The PM2.5 standard is the first ever set for fine particulates equal to or smaller than 2.5 microns in diameter.  The new standard will be implemented in addition to existing PM10 standards, which regulate larger particles.  

The new ozone standard limits the allowable level of ozone to 0.08 parts per million (ppm) averaged over eight hours.  The previous ozone standard limited the pollutant to 0.12 ppm over one hour.  When the EPA initially set the 8-hour ozone standard in 1997, it revoked the 1-hour standard.  However, while the legality of the standards was tied up in court, the 8-hour standard was reinstated.  

Although the EPA won a significant victory on how it sets air quality standards with the Supreme Court ruling, legal challenges still remain.  The high court invalidated the EPA's implementation plan for the 8-hour ozone standard and sent the case back to the Court of Appeals.  The EPA revised its plan to implement the new standard, consistent with provisions of the Clean Air Act.  Nonattainment designations for the new standard were made on April 15, 2004.  

Designation Status for New 8-Hour Ozone Standard

On April 15, 2004, EPA designated the seven county metro-Denver region - in addition to portions of Larimer and Weld Counties - as a deferred nonattainment area for the new health based standard.  Several local and state agencies signed an agreement with EPA called the Early Action Compact (EAC).  The EAC states that as long as the region submits a federally-enforceable State Implementation Plan outlining strategies to ensure compliance with the new standard by 2007, the nonattainment designation will be deferred.  The RAQC has been working with local and state agencies, as well as industry, to put together a plan.  The Ozone Action Plan was signed by the Governor in May of 2004 and must be submitted to EPA by December 31.  All the strategies outlined in the plan must be implemented before the end of 2005.      

1-Hour Ozone Standard

On July 5, 2000, the EPA reinstated the 1-hour ozone standard until the courts resolve legal issues surrounding the 8-hour standard.  EPA also reinstated the metro Denver area's previous designation as nonattainment even though the region has not violated the 1-hour standard since 1988.

However, on August 30, 2001, EPA Region 8 approved the "Ozone Redesignation Request and Maintenance Plan for the Denver Metropolitan Area."  EPA published the final rule for the approval of the plan in the Federal Register on September 11, 2001 - the last step in the approval process.  The redesignation was effective 30 days later on October 11, 2001.

The Plan demonstrates how the region will maintain the 1-hour National Ambient Air Quality Standard for ozone for at least the next 10 years.  Click on the link to view the "Ozone Redesignation Request and Maintenance Plan for the Denver Metropolitan Area."

The federal 1-hour ozone standard is 120 ppb, and a violation occurs when the 3-year average of exceedances is greater than 1 per year.

Denver Metro Area: Annual 4^th Maximum 8-Hour Concentrations (ppb)

*Violation: occurs when the 3 year average of 4^th maximum value recorded is equal to or greater than 85 ppb

• In the stratosphere, miles above the earth, ozone provides a beneficial "umbrella" to protect life from harmful solar rays. However, at ground level, ozone is harmful to breathe in high concentrations.
  
• The elderly, young children, and those with pre-existing respiratory infections are particularly at risk from exposure to ground-level ozone, but even healthy adults who spend a lot of time working or exercising outdoors may be affected by high ozone levels. Symptoms of ozone exposure include stinging eyes and throat, chest pains, coughing, and breathing difficulty.

• High levels of ozone present health concerns both for healthy adults and for sensitive people, particularly the elderly, young children, and those with asthma or other respiratory ailments. 
  
• Symptoms include stinging eyes and throats, chest pains, coughing, and breathing difficulty. 
  
• Young children are sensitive to elevated levels of ozone because they have developing respiratory systems and they breathe more air per body weight. 
  
• Healthy adults can experience health impacts as well, particularly if they spend significant time working or exercising outdoors when higher concentrations of ground level ozone are present.

There is no single source of ground level ozone pollution.  Ozone is a secondary pollutant, formed when volatile organic compounds (VOCs) react with nitrogen oxides (NOx) during the hot, still days of summer.  Pollution control strategies target these precursor pollutants. 

There are many sources of VOCs and NOx in the Denver metro region:

Because there are so many different sources of ozone precursors, the entire Front Range community must help solve the problem.  Private citizens, business, industry, and local governments can all contribute to the solution.  In this spirit the RAQC, in conjunction with other stakeholders, is working with a network of concerned citizens, business, industry, local governments, and health and environmental organizations to carry out its public awareness campaign to reduce summertime pollution.  Visit our "Keep It Clean" web page to learn more about our outreach and education efforts.    

For links to more information on ozone, visit our links library.