WASHINGTON (AP) _ In a setback for automakers, a government panel said Thursday the Environmental Protection Agency lacks authority to stop states from adopting tough vehicle-emission standards similar to those in California.
The National Academies' National Research Council said that California's role in setting emission standards has been scientifically valid and necessary because of persistent pollution in parts of the nation's most populous state.
The study, eagerly anticipated by the auto industry and environmentalists, examined emissions standards for mobile sources such as cars, light trucks and construction vehicles. The panel found that substantial progress has been made in reducing emissions but more needs to be done to meet federal air-quality standards in many parts of the country.
California, which began regulating pollution before the federal government, has the authority under the Clean Air Act to set its own vehicle pollution standards. States can adopt either the federal standards or California's rules, and some Northeastern and Western states have followed California's lead.
David Allen, a chemical engineering professor at the University of Texas at Austin and the panel's chairman, said Thursday that manufacturers told the committee about the costs associated with complying with both California and federal standards. But it was difficult for the committee to quantify those costs, he said.
Some environmental groups had feared the study might be used by Congress to put restrictions on states' abilities to choose the California regulations. But the committee said it disagreed over ways to improve the process by which states adopt California's standards.
``What role EPA is to have in the state adoption process is a policy decision that goes beyond scientific and technical considerations,'' the researchers said.
The report said the EPA needs to play a role in an improved process. The committee offered two recommendations: The EPA could help by providing formal but nonbinding guidance, or it could grant or (under limited circumstances) deny waivers allowing states to adopt the California rules. The panel disagreed over which would be most effective.
When the California Air Resources Board revises or sets an emission standard, it must seek a waiver from EPA. The study recommended that the EPA speed up waiver requests it considers noncontroversial and put a time limit on decisions that are more contentious.
Gary Marchant, a member of the panel and law professor at Arizona State University, said the committee recommended a time limit of two years for EPA review.
The report said California's standards, which are mostly stricter than those of the federal government, have helped push forward pollution-reducing technologies.
``California has used its authority as Congress envisioned: to implement more aggressive measures than the rest of the country and to serve as a laboratory for technological innovation,'' the report said.
Environmentalists said the study reaffirmed the role of states in reducing air pollution and global warming.
``We've learned the hard way that we can't always count on the federal government alone to protect our health and environment,'' said Frank O'Donnell, president of Clean Air Watch.
Bill Becker, the executive director of the State and Territorial Air Pollution Program Administrators and the Association of Local Air Pollution Control Officials, said the findings represented a ``tremendous victory for the preservation of states' rights.''
The Alliance of Automobile Manufacturers, in a statement, noted that the study recognized that vehicles are 99 percent cleaner than 1967 models because of reductions in smog-forming emissions.
``Automakers continue working hard to develop automobiles that are cleaner, safer and smarter than ever before,'' the industry group said.
The study was sought by Sen. Kit Bond, R-Mo., in 2003. While it was under way, California air regulators in September 2004 approved the world's most stringent rules to reduce greenhouse gas emissions.
The auto industry has challenged those standards in court.
The National Research Council is an arm of the National Academy of Sciences, an independent organization chartered by Congress to advise the government on scientific matters.