Center for Biological Diversity

Protecting endangered species and wild places through
science, policy, education, and environmental law.


Citizen Suit Filed to Protect Clean Air from Sulfur Dioxide Pollution, Reign in Bush Administration Foot-Dragging
U.S. Environmental Protection Agency Turning Blind Eye to Premature Death, Illness, Damage to Crops and Forests, Acid Rain, Ozone Depletion and Hazy Skies

For Immediate Release: February 6, 2005

Jeff Miller, Center for Biological Diversity, (510) 499-9185
Jeremy Nichols, Denver resident, (303) 437-7663
Robert Ukeiley, legal and technical questions, (859) 200-1325

Washington, DC – Conservation groups and citizens from across the country today filed a lawsuit against the U.S. Environmental Protection Agency (EPA) for failing to strengthen pollution limits on sulfur dioxide to protect clean air. Sulfur dioxide pollution harms human health, economic well-being and the environment, and is tied to premature deaths, respiratory illnesses, damage to crops and forests, acid rain and hazy skies. The groups filed a similar lawsuit in September 2005 over limits on nitrogen oxide emissions, which contribute to global climate change, increased toxic pollutant levels and ozone layer depletion.

“Our health, our communities and our natural places are in danger because of woefully inadequate limits on sulfur dioxide and nitrogen oxide pollution,” said Jeff Miller with the Center for Biological Diversity (CBD). “We have a right to clean, breathable air and meaningful limits on harmful pollutants – today’s lawsuit aims to make that happen.”

Sulfur dioxide is released primarily from coal-fired power plants, which are responsible for nearly two-thirds of all sulfur dioxide pollution in the United States. Sulfur dioxide contributes to respiratory problems, particularly for children and the elderly, and aggravates heart and lung diseases. It also plays a role in the formation of acid rain, which damages trees, crops and historical buildings. Sulfur dioxide is a component of haze, which impairs visibility in cities and many National Parks (see

Nitrogen oxides are highly reactive gases emitted primarily through the combustion of fossil fuels that contribute to health and welfare problems such as ozone depletion, global climate change, accumulation of excess nitrates in drinking water and acidification of soils. Elevated levels of nitrogen dioxide are also linked to asthma attacks and Sudden Infant Death Syndrome.

Under the Clean Air Act, the EPA has established National Ambient Air Quality Standards for sulfur dioxide, nitrogen oxides and four other major air pollutants (particulate matter, ozone, lead and carbon monoxide). The Act requires EPA to review these standards every five years to determine, based on the latest sound science, if they need to be strengthened or if additional air pollutants need to be controlled to protect human health and welfare. However, EPA has not reviewed sulfur or nitrogen oxide standards since 1996, nor changed sulfur standards since 1971.

“Like sulfur dioxide, the EPA’s foot-dragging stinks,” said Jeremy Nichols, a Denver resident and father of a three year old. “With our health and welfare on the line, the last thing the EPA should be doing is avoiding its responsibility to clean air.”

“The EPA’s current sulfur and nitrogen pollution limits are as outdated as the 8-track player,” said Peter Galvin, Conservation Director of CBD. “We deserve stronger standards to protect our communities and our environment.”

Extensive scientific evidence has emerged since 1996 concerning the detrimental effects of nitrogen oxides at levels allowed by the current standards, and a wealth of evidence indicates the 1971 sulfur dioxide standards are inadequate to protect the environment and human health. For example:

  • A 1974 study by the Tennessee Valley Authority found that sulfur dioxide pollution from just one coal-fired power plant damaged several species of pine trees, at hourly concentrations less than half of EPA’s standard;
  • The EPA admitted in a 1980 study that sensitive vegetation is damaged when sulfur dioxide concentrations average below the current daily and annual standards;
  • California already imposes a more stringent short-term sulfur dioxide standard of 0.25 parts per million, half the amount that the EPA allows under its secondary sulfur dioxide standard. Yet a survey of recent research on the adverse health effects of sulfur dioxide conducted for the California Air Resources Board found that the hourly limit of 0.25 parts per million was not sufficient to protect California residents (see

Under the Clean Air Act, citizens have the right to file suit in federal court to protect clean air. Today’s lawsuit was filed in the Washington, D.C U.S. District Court by the Center for Biological Diversity; Valley Watch, Inc. of the Lower Ohio Valley; Preston Forsythe of Muhlenberg County, Kentucky; Tina Johnson of Berea, Kentucky; and Jeremy Nichols of Denver, Colorado.

More Information Regarding Sulfur Dioxide Ambient Air Quality Standards:

  • Primary National Ambient Air Quality Standards (NAAQS) are established to ensure protection of human health. The NAAQS for SO2 are set at an annual arithmetic mean of 0.03 parts per million (ppm) and at a 24-hour limit of 0.14 ppm;
  • Secondary NAAQS are established to ensure protection of human welfare, including protection of vegetation, water quality and visibility. Secondary NAAQS for sulfur dioxide are set at 0.5 ppm over a three-hour averaging period;
  • Two sections of the Clean Air Act govern the establishment and revision of air quality criteria and NAAQS. Section 108 requires the EPA to identify pollutants that “may reasonably be anticipated to endanger public health and welfare” and to issue air quality criteria for those pollutants. Section 109 requires the EPA to establish primary and secondary NAAQS for pollutants identified under section 108, such as sulfur dioxide.
  • Section 109 requires that at five-year intervals the EPA “shall complete a thorough review of the criteria published under [section 108] and the national ambient air quality standards promulgated under this section and shall make such revisions in such criteria and standards and promulgate such new standards as may be appropriate.” Despite this clear requirement, it has been a decade since EPA last completed such a review to update the air quality criteria and NAAQS for sulfur dioxide.


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