Views are getting better at some of America's national parks, but that doesn't mean visitors will necessarily breathe easier.
New National Park Service data show that while visibility at some parks in the West has improved, ozone pollution has worsened significantly between 1995 and 2004 at 10 of them: Canyonlands, Craters of the Moon, Death Valley, Glacier, Grand Canyon, Mesa Verde, North Cascades, Rocky Mountain, Sequoia-Kings Canyon and Yellowstone.
The park service did not publicize the new findings, posted on its website, but a national environmental group said that, with summer visits by millions of Americans approaching, it was important to get the word out.
Breathing ozone can cause asthma attacks, lung inflammation and other respiratory illnesses. Ozone pollution also damages plants, including giant sequoias, other native vegetation and crops.
"The federal government's own monitors show that America's crown jewels like Yellowstone, Rocky Mountain and Grand Canyon national parks are at risk from worsening air pollution," said Environmental Defense senior attorney Vickie Patton. "We need thoughtful clean-air action to protect this precious legacy for our children and grandchildren."
John Bunyack of the National Park Service's air resources division, based in Denver, said the report showed various trends in air quality, depending on what was being measured.
"Some parks are going up in some areas, and some are improving in other areas," he said. "There are some areas getting worse and worse. Most people think they're going to go to a national park and experience clean, fresh, clear air, and that is not the case in many places. We're trying very hard to improve it, and I think we're making progress in some areas."
Ozone is a colorless, odorless pollutant, making it possible for visibility to improve sharply in Yellowstone National Park, for instance, even as ozone levels climb steadily. Brown haze and other visible smog has decreased in many parks because of a 1999 Environmental Protection Agency edict, Bunyack said, which has led to stiffer controls on industries that produce visible particulate pollution.
But Patton and Bunyack said that huge increases in oil and gas drilling in interior western states -- along with emissions from coal-fired power plants, cars and other sources -- were causing ozone to drift across some of the nation's most famous parks.
"We don't have any control over external sources," Bunyack said. "Although we do contribute with traffic ... most of the sources are outside the parks."
Environmental Defense and three other groups have sued the federal government in U.S. District Court to try to force air quality improvement changes in the Powder River Basin in Wyoming and Montana. The U.S. Bureau of Land Management has authorized 33 million acres of new oil and gas development there, with as many as 165,000 new coal-bed methane wells, despite testimony from other federal and state agencies that the project would lead to serious air pollution at Yellowstone, Grand Teton, Theodore Roosevelt, Wind Cave and other parks.
"There are immediate, cost-effective controls to limit pollution from the massive oil and gas activity across the West," Patton said. "They are proven, they're used in a number of technologies, but the BLM is not asking any of the proponents ... to thoughtfully mitigate the serious air pollution impacts."
In addition to parks with worsening conditions, Joshua Tree National Park was among those whose unhealthy air pollution levels remained constant. The full report is available at www2.nature.nps.gov/air.