Press Release Mar 23, 2010

Groups Ask EPA to Ensure New Ozone Standards Protect National Parks

Ground-level ozone damages park ecosystems

Washington, D.C. – In an effort to better protect national parks and their visitors from air pollution, the National Parks Conservation Association (NPCA), the Appalachian Mountain Club (AMC), and other groups filed comments on Monday asking the U.S. Environmental Protection Agency (EPA) to approve the most protective ground-level ozone standards under consideration. The groups also applauded EPA’s plan to establish new ozone rules to protect trees and other plants from ozone damage in addition to those designed to protect human health.

“Ozone is an unwelcome visitor to many national parks in the summer, causing ‘code red’ warnings against vigorous outdoor activities,” said Mark Wenzler, NPCA director of clean air and climate programs. “This same lung-damaging pollutant also causes serious harm to plants in Acadia, Great Smoky Mountains, Yosemite and other national parks across the country.”

Ground-level ozone, the main component of smog pollution is formed when automobile, industrial, and coal-fired power plant pollution are exposed to heat and sunlight. While ozone that forms in the upper atmosphere helps to protect us from harmful radiation, ground-level ozone can worsen asthma, damage the developing lungs of children, and cause premature death from heart and lung disease. Ozone damages and kills iconic species such as the black cherry tree in the East and aspen and ponderosa pine in the West, and national park ecosystems across the country show damage from ground-level ozone pollution.

EPA is currently revisiting its National Ambient Air Quality Standards (NAAQS) for ground-level ozone following a lawsuit by NPCA and other organizations that charged the agency ignored scientific findings and implemented standards that were too weak to adequately protect people and the environment.

In addition to establishing lower maximum levels of ozone allowed over a certain time period to better protect public health (the “primary standard”), EPA will issue a “secondary standard” designed to protect plants and animals. This is the first time that EPA has ever proposed a secondary standard to protect ecosystems, despite a long-standing mandate in the Clean Air Act to do so.

In their comments, the groups urged EPA to consider both day and night-time exposures to ozone instead of only daytime, and to calculate exposures over a region’s growing season, instead of only for three months, to better account for the impacts on plants. They also recommend periodically updating the defined growing season as climate change causes them to lengthen.

“We are very encouraged by EPA’s proposal to set a distinct secondary ozone standard focused on ecosystems protection,” said Georgia Murray, AMC Air Quality Staff Scientist. “However, to be fully protective of highly-valued recreational destinations, like Great Gulf Wilderness in New Hampshire and Acadia National Park in Maine, EPA must consider that peak ozone levels often occur at night in these and other protected lands. Excluding this night-time exposure from the cumulative standard or limiting it to a three-month window will underestimate the ozone-caused damage and stress plants experience in these special areas.”

The groups also recommended setting aside additional funding for ozone monitoring in national parks, wilderness areas and higher elevations, where data on ozone exposures is lacking. They further ask that EPA choose the most protective primary standard under consideration to better protect people who engage in outdoor recreation, including hiking, which would cause them to have longer and higher ozone exposures.

The comments can be viewed online by clicking here.


About National Parks Conservation Association
Since 1919, the nonpartisan National Parks Conservation Association (NPCA) has been the leading voice in safeguarding our national parks. NPCA and its more than one million members and supporters work together to protect and preserve our nation’s natural, historical, and cultural heritage for future generations. For more information, visit

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