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Ozone Trend Analysis Shows Continued Progress

Release Date: 04/28/2004
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Contact: John Millett 202-564-7842 /

(Washington, D.C. - April 28, 2004) Less than a week before people around the globe will mark World Asthma Day, U.S. EPA analyses shows that ozone levels nationwide are the lowest they have been since 1980. The improved air quality results mainly from continuing reductions in emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) – the pollutants that combine in the summer heat to form ozone.

“Every American can be proud of our nation’s progress in cleaning up the air,” said EPA Administrator Mike Leavitt. “We have a national strategy to clean the air that is working. The next steps in this strategy are to work with states to meet the new, more protective standards, clean up old power plants and remove the sulphur from diesel fuel. These actions, when combined with other measures, will ensure that Americans continue to breath cleaner air.”

EPA’s analyses of ozone air quality trends, which will be released May 4, summarizes the state of ozone air quality for 2003 and examines trends in monitoring and emissions data since 1980. The report will show that ozone levels across the nation were down substantially in 2003. In fact, many areas of the country experienced their lowest ozone concentrations since 1980. The improved air quality resulted mainly from favorable weather conditions and continuing reductions in emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) – the pollutants that combine in the summer heat to form ozone. Changing weather patterns contribute to yearly differences in ozone concentrations from region to region and it is important to look at trends over longer periods of time.

Emissions of NOx and VOCs have decreased 54 and 25 percent, respectively, since 1970. This environmental progress comes even as the country has experienced a 176 percent increase in gross domestic product, a 45 percent increase in energy consumption and a 155 percent increase in vehicle miles traveled.

The vast majority of counties, 2,668 in all, meet new ozone standard designed to protect people from longer term exposure to lower levels of ozone. However, earlier this month EPA designated part or all of 474 counties as not meeting the more protective national 8-hour ozone air quality standard. “Our efforts to clean up the air must be ongoing,” said Leavitt. “We will continue to make progress by setting national standards, providing tools for local solutions and ensuring no backsliding.”

The Bush Administration recently announced a sweeping set of actions – the Clean Air Rules of 2004 – to help all areas across the country significantly improve ozone air quality. Many national clean air actions will bring local areas into attainment without any additional local controls. These national clean air control programs include:
        • EPA's regional ozone transport rule, known as the NOx SIP Call, will significantly reduce NOx emissions in 19 eastern states and the District of Columbia by approximately 600,000 tons starting in the summer of 2004 and by nearly 1 million tons when fully implemented.
        • EPA's proposed Clean Air Interstate Rule would bring many areas into attainment with the fine particle and ozone standards. EPA expects to issue this as a final rule in late 2004.
        • Clean Air Diesel Rules targeting diesel emissions from on road and off road diesel engines will help to significantly cut NOx emissions nationwide.
        • EPA is phasing in very stringent tailpipe standards for gas-engine cars, trucks, and SUVs that also reduce NOx and VOC emissions.

A fact sheet, Summary Facts on Ozone Trends, which includes a graph on ozone trends and separate table titled, Air Quality Improvement in Major Cities are available at: .

Recent information on ozone designations and the Clean Air Rules is at: . EPA's new Summary Ozone Trends Report will be available on May 4, and additional information on ozone is available online at: .