The National Park Service today banned the recreational use of snowmobiles in nearly all national parks, recreational areas, and monuments, saying they have had a “significant adverse environmental effect” on the park system. The only exceptions are parks in Alaska and Voyageurs National Park in Minnesota, where Congress has specifically allowed snowmobiles. More than 180,000 snowmobiles have been used during winter months in the national park system and critics argue that they cause significant air pollution, noise, and disruption to wildlife. The NPS decision came in response to a petition filed more than a year ago by a coalition of enviro groups. A report released today by the EPA found that while air quality in the U.S. improved overall between 1989 and 1998, pollution rose significantly in a number of national parks.