ANCHORAGE (AP) -- The air at Denali National Park and Preserve is ranked the cleanest in the nation based on the results of a federal air quality monitoring program.
Even with Alaska's natural dust and wildfires, the state scored the best out of 30 sites around the country, said Cathy Cahill, an atmospheric chemist at the University of Alaska Fairbanks Geophysical Institute.
''We come out as the cleanest,'' she said.
The program, called the Interagency Monitoring of Protected Visual Environments, is sponsored by the National Park Service, Fish and Wildlife Service, Bureau of Land Management, U.S. Forest Service and the Environmental Protection Agency. It grew out of amendments to the Clean Air Act that aimed to prevent and fix impairments in visibility resulting from man-made air pollution, according to the Park Service.
The program is growing to include more than 100 sites, said Andrea Blakesley, a Park Service environmental specialist at the Denali air station. Alaska could have three more monitoring sites, she said, including Trapper Creek and Sand Point.
The Denali station, near the park entrance, has been part of the program since 1988, Cahill said. Twice a week, scientists use a vacuum pump system that pulls air through four filters and traps small pollution particles, she said. Samples from all the sites are analyzed by the same agency and then ranked accordingly.
The results are based on data collected from 1994 to 1998. Samples are still being collected, but more recent data have not been analyzed.
The station also monitors the air for ground-level ozone and acid rain. In total, the Denali station is involved in four national air monitoring programs and one state program, Blakesley said.
The Denali monitoring system records the most pollution in summer, at the peak of the fire season, when smoke from wildfires swirls across much of the Interior.
''Our really bad days can be really bad,'' Blakesley said, referring to the wildfire smoke. ''But there is a difference. Our worst days are caused by natural factors.''
''The pollution that we worry about more is coming over'' from other countries, she said. The station catches man-made pollution that drifts across the Pacific Ocean from Europe and Asia.
''We are kind of in a neat situation because we get to see what is going on in other places in the world by looking at our air.''
As China becomes more industrialized, Cahill said, the emissions from power plants might affect the quality of air in Alaska.
''It is something to pay attention to, and having a long-term monitoring system helps,'' she said.
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