EPA's Ozone Rule Violates Clean Air Act

January 2007

A three judge panel on the U.S. Court of Appeals for the D.C. Circuit ruled on December 22 that the 8-hour ozone rule that EPA implemented in 2004 violates the Clean Air Act. States, environmental groups and industry sued the EPA over various provisions in the 2004 Rule. Holding that "EPA's interpretation of the Act in a manner to maximize its own discretion is unreasonable because the clear intent of Congress in enacting the 1990 Amendments was to the contrary," the court vacated portions of the 2004 rule and remanded it to the EPA. The court specifically took issue with EPA treatment of areas that fall between the old 1-hour ozone standards and the 8-hour ozone standards, and determined that the 2004 rule violates anti-backsliding provisions of the Clean Air Act by allowing certain controls to be removed from state implementation plans.

The Clean Air Act requires the Environmental Protection Agency to set National Ambient Air Quality Standards (NAAQS) for six pollutants including ground-level ozone. Ozone is formed when Nitrogen Oxide (NOx) combines with Volatile Organic Compounds (VOCs) and sunlight. Ozone is a primary ingredient in smog and is harmful to human health, especially those with preexisting health problems like asthma, children and the elderly. In 2004 EPA replaced the 1-hour ozone standards with the 8-hour ozone standard. Areas that do not meet the standards for ozone are designated nonattainment areas and states are required to implement measures to reduce ozone causing emissions. For more information on EPA's ozone standards, visit the EPA website. Click here for a map of 8-hour designations by region.

Click here for the court's opinion.

Environment News Service Article

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