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EPA Issues New Ozone Recommendations

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February 2007

In a report released on January 31, 2006 staff scientists at EPA recommended reducing the primary ozone standard from .080 parts per million (ppm) to .060 ppm. "The overall body of evidence on ozone health effects clearly calls into question the adequacy of the current standard," said EPA in a fact sheet released with the report. Of particular concern are those people who are considered especially sensitive to the health effects of ground level ozone, including people with asthma and other lung diseases, the elderly, children and adults who are active outdoors, and outdoor workers.  The report also recommends making changes to the secondary ozone standards.  Primary standards protect human health, secondary standards are designed to protect welfare, including harm to vegetation.

The recommendations have been met with mixed reviews from observers outside of EPA.  If the EPA Administrator were to adopt the recommendations and impose more rigid ozone standards, it is highly likely that many more areas in the United States would be considered nonattainment areas under the Clean Air Act; i.e., areas that are in violation of the ozone standard.  Currently, over 110 areas in 31 states are considered nonattainment for ozone.

Under the Clean Air Act, the Environmental Protection Agency (EPA) is required to periodically review its air quality standards to determine whether they still protect human health and the environment.  EPA is further charged with making changes to air quality standards if necessary.  As part of the review process, staff at the EPA prepared the "Review of National Ambient Air Quality Standards for Ozone," which is the first of several papers.  EPA last revised its ozone standards in 1997.

Ground level ozone is formed when volatile organic compounds (VOCs) combine with nitrogen oxides (NOx) in the presence of sunlight, and is a primary component of smog.  VOCs and NOx are emitted from both stationary sources such as power plants and mobile sources such as automobiles.  Ozone concentrations are highest in the summer months corresponding with higher temperatures and solar radiation.  While ozone is beneficial in the stratosphere where it helps protect the earth from the sun's harmful UV rays, it is harmful when breathed and can cause significant damage to vegetation.

EPA Fact Sheet and paper

 Air Quality