A bipartisan group of U.S. senators has notified the director of the U.S. Environmental Protection Agency that they will find legislative solutions to provide clean air over national parks if his agency can't protect those airsheds.

"Congress made a firm commitment to protect air quality in America's national parks and wilderness areas to that visitors can enjoy clear skies and healthy air," reads the letter to Stephen Johnson that was signed by senators Lamar Alexander, R-Tenn., Jon Tester, D-Mont., Ken Salazaar, D-Colo., Thomas Carper, D-Del., Judd Gregg, R-NH, Benjamin Cardin, D-Md., Elizabeth Dole, R-N.C., and John Warner, R-Va. "If EPA puts Class I air quality at risk by adopting this flawed rule-making, we will pursue legislative options to restore the full level of protection provided by the Clean Air Act.

"We urge you to remove this rule-making now to avoid a legacy of dirty air in our national parks and wilderness areas."

The proposed rule-making the senators referred to would make it easier to build coal-fired power plants near national parks, and weaken existing air-quality standards.

The National Parks Conservation Association today held a trio of news conferences across the country to highlight the threats the proposed rule poses.

"Great Smoky Mountains National Park already suffers from poor air quality and today has an 'orange alert' pollution warning," said Cocke (Tenn.) County Mayor Iliff McMahon, Jr., who spoke at a press conference in Knoxville, Tennessee. "Poor air quality affects the experiences and health of summer visitors, which affects our economy. It doesn't make sense for the administration to encourage more polluting coal-fired power plants to build in the Smokies' backyard. Especially when we are already doing everything possible to improve our air quality."

Under current regulations, one in three national parks already suffers from air pollution levels that exceed federal health standards, according to NPCA. Much of that pollution comes from burning coal, the advocacy group said. In June, the NPCA's Dark Horizons report named Great Smoky Mountains as one of ten national parks most at risk from pollution from new coal-fired power plants.

"Our national parks were set aside as symbols of our national heritage and freedom," said Don Barger, senior director of the NPCA's Southeast regional office. "Instead of opening the door to more pollution in national parks such as Great Smoky Mountains and Zion, the EPA should be working to secure a legacy that preserves America's treasures for our children and grandchildren."

National Park Service officials are aware of the poor air quality that already exists over many Western parks. Back in February the agency released a report, six years in the making, that pointed out that from Alaska to the U.S.-Mexico border fish being pulled from national park waters are showing alarming concentrations of heavy metals and pesticides.

The study of airborne contaminants in national parks across the western United States would seem to demonstrate that there's virtually no place in the Northern Hemisphere that can avoid contamination from pesticides and heavy metals. In some cases, mercury levels in fish were found to be far above human-health standards set by the EPA, according to the Park Service.

The study said some of the depositions were from local and regional sources, both past and present, while others were carried from Europe and Asia across the Pacific by trade winds.

According to the most recent federal data, park visitors spent $10.7 billion in the gateway towns and regions surrounding national parks in 2006, supporting about 213,000 jobs. NPCA officials say that for gateway communities that depend on these parks, worsening air quality could have devastating local economic impacts.

According to the group, the EPA's proposed changes would allow large polluters such as coal-fired power plants to manipulate their data to mask pollution spikes and make it appear as if the air in the region surrounding national parks is cleaner than it actually is.

Park Service scientists have criticized the proposed rules as providing "the lowest possible degree of protection" for park air quality. EPA scientists have also objected to the rule change, calling it "grossly inadequate," and opening the door to "totally frivolous documentation" of emissions from coal-fired power plants that would "seriously underestimate" pollution increases at affected national parks.