The Environmental Protection Agency, under congressional pressure to crack down on air polluters in the aftermath of a chemical leak that killed 2,000 persons in Bhopal, India, unveiled a new strategy yesterday that puts most of the burden for enforcing toxic air pollution controls on state and local governments.

The plan, which calls for no new federal regulation of the chemical industry, was immediately denounced by environmentalists and congressional critics.

EPA administrator Lee M. Thomas said the chemical industry has "a strong safety record" in this country.

He said nonindustrial sources, such as motor vehicles, wood stoves and dry cleaners, account for three-fourths of all so-called "air toxics," and pose a greater threat to the air than do industrial plants, which "are not the major sources" of cancer-causing pollutants in the air.

Thomas said the new policy, the result of a two-year study, will encourage state and local governments to develop standards that meet the particular concerns of their respective communities.

David Doninger, of the Natural Resources Defense Council, said the EPA "has turned its longstanding failure to protect public health from passive neglect into deliberate policy."

One state regulator, Carl Beard, director of West Virginia's Air Pollution Control Commission, said states need federal assistance in evaluation of hazardous wastes. "We don't have the resources to evaluate volatile organic compounds. There are hundreds in West Virgina and thousands across the country."

While most of the plan deals with routine releases of toxic substances, a special section was prompted by the catastrophe last December at the Union Carbide Corp. plant in Bhopal.

It calls for greater federal support of local emergency preparedness plans, preparation of a list of about 100 substances that are likely to cause harm if discharged into the atmosphere in large amounts, and help in developing community right-to-know programs.

But Thomas said he saw no need for specific controls on methyl isocyanate, the chemical that caused the Bhopal tragedy, "because it is manufactured at only one site in this country," at Union Carbide's plant in Institute, W.Va. West Virginia's Beard said he is worried that "if one state cracks down hard, the industry tends to go to states with less requirements. This creates a pollution haven in some states." He said the Clean Air Act was written to redress variations in state enforcement policies.

Thomas said he was not concerned that a lack of federal regulation might result in "state shopping" by polluters, or that some depressed areas would relax standards to retain such industries.

"I don't think we can force local governments to set a regulation on a particular industry if they want to allow an excess cancer rate in their community," Thomas said, but he added that "what I'm finding is that the communities absolutely want to control them."

Sens. Frank R. Lautenberg (D-N.J.) and Daniel Patrick Moynihan (D-N.Y.), in a letter to Thomas, said the plan "appears to absolve the agency from responsibility . . . as mandated by the Clean Air Act."

Rep. James J. Florio (D-N.J.) said, "They cannot unilaterally do this. What they're effectively doing is delegating to the states responsibilities Congress has given to the EPA. It really makes no sense to deal with clean air or clean water on a state-by-state basis."

Rep. Henry A. Waxman (D-Calif.), chairman of the House subcommittee on health and the environment, called the EPA strategy "bad policy based on bad science."

The EPA also announced yesterday that it is adding chromium to the list of six air pollutants that have been found to cause cancer in humans and should be controlled under the Clean Air Act.

The agency also said it had concluded that three other substances, methyl chloroform, chlorofluorocarbon (CFC)-113 and epichlorohydrin, should not be added to the list.