Summer vacationers who think they're getting away from it all by going to America's national parks and tourist attractions should know there's one problem they haven't left behind--air pollution.

Ozone levels on the northern tip of Cape Cod were triple those recorded in Boston this summer; historic Annapolis has had four times as many bad air days as Baltimore; and peak ozone levels in Williamsburg exceeded those in the District, according to a new report by the Clean Air Network, a project of the Washington-based Natural Resources Defense Council.

"We issue ozone advisories like a city would. . . . We have to tell people to 'breathe at your own risk,' and that's pretty sad for a national park," said Jim Renfro, a National Park Service air resources specialist stationed at North Carolina's Great Smoky Mountains National Park. Ozone levels there this summer exceeded those of every southern city except Atlanta, according to the report. Kiosks at the visitors centers allow tourists to check the park's current ozone readings via computer.

From the ridge tops of the Smokies to the beaches of Maine, ozone levels this season have been as high or higher than those recorded in large cities, according to Jayne Mardock, one of the authors of the report, entitled "No Escape--A Midsummer Look at Ozone Smog in 1999."

Ozone is created when heat and light interact with nitrous oxide released by power plants and automobiles and volatile organic compounds that come from paint and solvents. These constituent elements can be carried for miles by gusts of air. Ozone aggravates asthma and other respiratory conditions, inflaming the small airways in the lungs, causing wheezing, coughing and, in some cases, scarring of lung tissue.

Officials at the National Park Service are studying the problem, confronted as they are with an alarming rise in air pollution in many of their parks across the country, with the Smokies and Shenandoah National Park near the top of the list.

Smog drifts up and hovers at the higher elevations where parks like the Smokies are located, Renfro said. "Southwesterly airflows blow smog from the Tennessee Valley to the Smokies. The Shenandoahs get it from Washington, D.C., and the Ohio River Valley," said Don Shepherd, an environmental engineer for the Park Service's Denver office. Weather patterns also can trap the smog near the coast.

"The lesson from this is, there is no way to get away," Mardock said. "The wind blows; it's almost everywhere."

Her group surveyed available government data from 32 states and the District of Columbia through July of this year. The study analyzed the number of times the Environmental Protection Agency's ozone standard was exceeded, based on the average ozone readings over an eight-hour period.

The report said there were 11 high-ozone days recorded at the northern tip of Cape Cod this year, compared with four in Boston.

Amish country in Lancaster, Pa., had nearly twice as many dirty air days (14) as Philadelphia (8), and the Eastern Shore of Maryland had peak levels as high as those recorded in downtown Washington.

Moving north, the Hamptons had about the same number of bad air days as New York City, and Acadia National Park in Maine had ozone readings on a par with Philadelphia's.

Federal officials say they are increasingly concerned by their own data showing that air pollution is on the rise and moving beyond the boundaries of big cities. "There are more and more ozone problems showing up outside of urban areas," said Kristeen Gaffney, an environmental scientist with the EPA's mid-Atlantic regional office.

Reaction to the report ranged from vigorous concurrence to snorts of derision from local officials and tourism boosters.

"You've got to wonder what kind of whacked-out, bad-science report that is," sputtered Tom Roskelly, public relations spokesman for Annapolis. "I find that laughable. The air here is as good as it could be. And that is not the case in Baltimore. I go up there for ballgames, so I know."

The editor of a Cape Cod newspaper said he finds the air in Provincetown, Mass., "magnificent." The report, which created a stir in the resort community this summer, struck him as "perplexing."

"All I can think of is, it's one of those the-sky-is-falling things by some group with an agenda," said Duane Steele, editor and publisher of the Advocate. Steele acknowledges that his reporters corroborated the data with Massachusetts officials.

The report comes as no surprise to North Carolina's Renfro. He calls air pollution "the number one issue we have at the Smokies" and said he sees its effects every day, from the damaged, stunted foliage to the park visitors confronting health problems.

On their worst air-quality day ever last August, the equivalent of a Red Alert day in Washington, he recalled, an asthmatic girl hiking the Appalachian Trail had to be transported to a hospital.

"Both her inhalers didn't work. She was in trouble," he said. "It's hard to draw conclusions from one case, but it sure makes you think."