 President George W. Bush's decision to intervene in setting air pollution standards is part of a longstanding administration pattern of meddling in environmental science, watchdog groups said on Friday. In cases this week dealing with polar bears, ozone smog and environmental research, groups that monitor these decisions faulted the Bush administration for slighting science in favor of politics. Bush overruled officials of the Environmental Protection Agency to weaken U.S. standards for smog-forming ozone meant to protect parks, crops and wildlife. On Wednesday, the agency tightened a different ozone standard aimed at protecting human health, but not as much as its own scientists unanimously recommended. Asked why the president intervened, White House spokesman Tony Fratto said: "What we were trying to do on the smog decision was try to have a decision that was consistent with our interpretation of the statute. This was not a weakening of regulations or standards governing ozone, but it was an effort to make those standards consistent." Environmental and scientific groups disagreed, saying the decision benefits coal-fired power plants and other industries that emit ground-level ozone. In addition to harming plants, ozone smog endangers human health, especially the young, the elderly and those with respiratory problems. "This is a pattern unfortunately that extends across the Environmental Protection Agency, across pretty much every science based agency in the federal government," said Tim Donaghy of the Union of Concerned Scientists. 'AN EPIDEMIC OF INTERFERENCE' "In the last several years, there has been an epidemic of interference in the work of scientists," Donaghy said by telephone. "And often this happens because interfering in the science is an easy way in winning the battle over the policy." The Clean Air Act, which includes the ozone standards, forbids consideration of any other factor but science in making this kind of decision. But in announcing the new standards on Wednesday, EPA chief Stephen Johnson suggested the act should be changed to include economic factors. The ozone decision showed that "real science appears to have been tainted by political science," said Frank O'Donnell, president of Clean Air Watch. Mark Wenzler of the National Parks Conservation Association concurred. "The scientists carefully explained what needed to be done to protect plants and wildlife and the administration completely ignored the science and decided it would protect industry from having to do anything in addition to what they're doing," he said. On another front, the EPA drew criticism for closing some of its 26 research libraries to save money. The Government Accountability Office, the investigative arm of Congress, said the changes "could have impaired the continued delivery of library materials and services to its staff and the public." In practice, the library move meant scientists who can't get to EPA libraries have to go online, where only about 10 percent of the agency's collections are available. On Monday, environmental groups sued the Interior Department for failing to meet a court deadline to decide whether polar bears are threatened by climate change under the Endangered Species Act. The EPA said its lawyers were still considering the case. 