Both reports blame fossil fuel burning power plants, industrial facilities and motor vehicles for generating the smog and haze that threatens the health and beauty of the nation's parks.

The National Park Service (NPS) report "shows that in most parks, air quality exceeds standards set by the Environmental Protection Agency to protect public health and welfare," said NPS Director Fran Mainella. "Our findings also show that some parks occasionally experience pristine air quality conditions, unaffected by air pollution."

The best visibility, the NPS report found, occurs in Denali National Park in Alaska, and in an area centered around Great Basin National Park in Nevada.

However, Mainella acknowledged that more work needs to be done to improve air quality and visibility at many national parks. Air pollution now impairs visibility to some degree in every national park, she noted.

In 1977, Congress amended the Clean Air Act to establish a national goal of cleaning up the air over national parks and wildlands, called Class I areas. That goal has yet to be reached.

"Information in this report will help us to protect air quality related values from the adverse effects of air pollution by communicating information about air quality conditions in parks to the public and to state, federal and tribal authorities," Mainella said.

For more than 20 years, the NPS has been studying air quality in national park areas, with monitoring now underway at 60 NPS sites. The NPS air quality monitoring program provides information on ozone levels, acid rain and visibility impairment in parks.

The NPS report found that from 1990 to 1999, of the 28 parks that were monitored for visibility, 22 had improving visibility conditions on the clearest days. Ground level ozone concentrations were monitored at 32 parks, and the results show that while ozone levels in eight parks are improving, in 16 parks they are getting worse.

Acid rain monitoring was conducted in 29 parks, including testing for levels of sulfates and nitrates in rain and snow. Twenty-five parks are showing a decrease in sulfate levels, while 14 show a decrease in nitrate levels, the NPS report found.

The NPS report agreed with the report issued by the conservation groups in ranking the parks with the worst air pollution problems. "Code Red: America's Five Most Polluted National Parks," a report produced by the National Parks Conservation Association (NPCA), Appalachian Voices, and Our Children's Earth, uses an air pollution index, developed by Appalachian Voices for two earlier studies, to rank the five most polluted national parks based on haze, ozone and acid precipitation.

"In the Great Smoky Mountains, our most polluted national park, ozone pollution exceeds that of Atlanta, Georgia, and even rivals Los Angeles, California," said Harvard Ayers, chair of Appalachian Voices, a nonprofit conservation group focused on protecting forests and communities of the Appalachian Mountain region.

Besides Great Smoky Mountains National Park in Tennessee and North Carolina, the "Code Red" report names Shenandoah National Park in Virginia, Mammoth Cave National Park in Kentucky, Sequoia-Kings Canyon National Parks in California, and Acadia National Park in Maine as the parks with the nation's worst air pollution.

All of these parks are also cited in the NPS report, titled "Air Quality in the National Parks."

The ways in which air pollution harms the parks varies. At Great Smoky Mountains, for example, ozone pollution has violated federal health standards more than 175 times since 1998 and is damaging 30 species of plants. Acidic mountaintop clouds blanket spruce and fir tree forests, and saturate soils with excess nitrogen.

At Shenandoah National Park, visibility from Skyline Drive and the Appalachian Trail has shrunk to as little as one mile on smoggy summer days, and acid precipitation is ruining streams for native fish. At Sequoia and Kings Canyon National Parks, ozone levels surpassed human health standards on 61 summer days in 2001, posing a risk to sequoia seedlings and blocking views of the Sierra mountain scenery.

The NPS report confirms that ozone injury to vegetation has been documented at Ozone injury to vegetation has been identified in Shenandoah, Great Smoky Mountains, Sequoia and Kings Canyon, as well as two additional national parks in California: Yosemite, and Lassen Volcanic National Park.

At Acadia National Park, scenic views are impaired and acid rain threatens streams and lakes. Acid rain is also a major problem at Mammoth Cave National Park, where it seeps through the porous karst rock to pollute underground streams and the unique wildlife that depends upon them.

The impacts of air pollution are evident throughout the National Park System, charge the groups behind the "Code Red" report. For example, Big Bend National Park in Texas was found to have some of the worst visibility in the western states, and air pollution at this park along the Mexican border is growing worse. Many other parks are not included in the report because they lack complete monitoring data, the groups noted.

Other types of air pollution, such as mercury deposits, pose risks at parks ranging from Acadia to the Everglades in southern Florida. Airborne pesticide residues from agricultural areas threaten park wildlife, the groups warn, and global warming caused by emissions of greenhouse gases could disrupt ecosystems in national parks.

Most park air pollution from human sources comes from burning fossil fuels such as coal, oil and natural gas, both reports agree. Power plants and industrial facilities, as well as cars, trucks, planes, trains and construction equipment, all produce fossil fuel pollution.

Power plant emissions vary by region, but this one industrial sector ranks among the worst polluters, particularly in the eastern half of the country, the reports note. For example, sulfate particles formed from sulfur dioxide emissions from fossil fuel combustion - mostly from electric generation facilities - accounts for 60 to 80 percent of the visibility impairment in the eastern parks and 30 to 40 percent of the impairment in western states, the NPS report states.

Besides damaging visibility and natural resources at national parks, this pollution can also harm human health.

"New statistics from the World Health Organization show that in the United States, air pollution annually kills nearly twice as many people as do traffic accidents and that deaths from air pollution equal deaths from breast cancer and prostate cancer combined," said Tiffany Schauer, executive director of Our Children's Earth Foundation.

The "Code Red" report also assesses progress made during the decade since the passage of 1990 amendments to the Clean Air Act, the most recent changes to the law.

"National parks have seen little to no improvement despite the most recent amendments to the Clean Air Act," said Don Barger, NPCA's southeast regional director. "For example, pollution from outdated power plants continues to harm parks and people, when there's no reason older power plants cannot meet modern pollution control requirements."

NPS Director Mainella says the agency is working to improve air quality in parks by promoting pollution prevention practices in parks and reviewing permit applications for new and modified air pollution sources near parks. Yet just last month, the Department of Interior approved plans for a new coal fired power plant in western Kentucky that critics charge will increase air pollution at nearby Mammoth Cave National Park, which already suffers from some of the worst visibility in the nation.

The "Code Red" groups argue that the Bush administration could, and should, be doing more to clean up the air over national parks.

"Air pollution in the national parks is a national crisis that requires national solutions," said Joy Oakes, director of NPCA's Clean Air for Parks and People campaign. "A key part of the solution is for the Bush Administration to enforce existing pollution laws. Unfortunately, the Administration is abandoning programs essential to cleaning up the air in our parks and communities."

The groups argue that the Bush administration must implement and enforce existing programs of the Clean Air Act, such as the Regional Haze Rule, including the Best Available Retrofit Technology (BART) amendment and the New Source Review program.

Current Bush administration proposals would eliminate these basic programs, weakening provisions to protect parks, the groups charge, while President George W. Bush's plan for clean air protection, called the Clear Skies Initiative, will not do enough to protect air quality in national parks, the report says.

"Code Red" also makes a case for new federal legislation that would make "sizeable cuts in power plant emissions," including sulfur dioxide, nitrogen oxides, mercury and carbon dioxide. New legislation is also needed to cut emissions from mobile sources such as cars and trucks, and to increase the fuel efficiency of motor vehicles.

Until these actions are taken on the federal level, the "Code Red" report urges states to find ways to protect themselves, such as controlling in state sources of pollution. Several states are already moving in this direction, the report notes. Earlier this year, California became the first state in the nation to control greenhouse gas emissions from tailpipes.

In June, North Carolina passed the Clean Smokestacks Act, requiring the state's power plants to slash sulfur dioxide emissions by 74 percent, and nitrogen oxide emissions by 78 percent. Similar legislation has been introduced by Democrats in the U.S. House and Senate, but has been stalled by Republican and White House opposition.

"Ironically, as North Carolina takes steps to improve air quality, the Bush Administration has proposed a major step backward - actually weakening the Clean Air Act," noted U.S. Representative David Price, a North Carolina Democrat. "So even though North Carolina will be doing its part to reduce pollution that causes ozone and acid rain, our state will continue to be stricken by pollution coming from other states."

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