General Motors, in a decision critics say could markedly affect highway death and injury tolls, reversed itself and said yesterday that it will not offer air bags on its full-size 1982 cars.

Instead, GM will meet federal safety rules by providing so-called automatic safety belts for the driver and one front passenger. Each will occupy a separate seat; the cars will accommodate only two occupants in front. No automatic belt has been devised that can protect center front-seat passengers.

Under a 1966 law, the Department of Transportation is now requiring that 1982 models of some cars be equipped with passive restraints, which protect vehicle occupants with no action on their part. But the department is leaving it to the manufacturers to chose between automatic belts and air bags.

Automatic belts wrap themselves around a person as he enters the front passenger compartment and shuts the door.

Air bags are out of sight under the dash until the instant when a frontal collision inflates them into cushions.

Air bags cost more, but proponents say they also are safer, for these reasons: automatic belts in existing cars have been such a nuisance to many owners that they have snipped the webbing or otherwise "defeated" them. And bags in high-speed crashes are less likely to cause abdominal or neck injuries and do a better job than belts in spreading the impact over the entire body.

GM Washington press spokesman R. T. Kingman Jr. told a reporter, however, that the decision not to offer air bags "should have no effect on death and injury rates."

By Contrast with GM, Mercedes-Benz has told DOT's National Highway Traffic Safety Administration that it will equip all of its 1982 cars with air bags, although only one of the three lines of cars it sells here will be required to have passive restraints in that model year.

In Detroit, the Ford Motor Co. said that belts will be standard equipment on its 1982 large cars, defined by NHTSA as having wheelbases longer than 114 inches, but the air bags will be an option on "luxury" versions starting with the "1981 1/2" models.

Chrysler Corp. said it isn't prepared to say if it will produce large 1982 models, but that if it does, the cars will have automatic belts.

The GM decision was disclosed by president Elliot M. Estes in a telephone call Monday to DOT Deputy Secretary William J. Beckham Jr. In December, GM officials had assured DOT that "we plan to offer the fully inflatable [air bag] as an option on the 1982 large-sized cars."

In reply to questions, GM's Kingman told a reporter that Estes made the call after discussing the matter with the board of directors, which was holding its monthly meeting, and its public policy committee.

The committee chairman, the Rev. Leon H. Sullivan, told The Washington Post he did not remember having seen the issue on the agenda and that it was not discussed before he left the meeting -- about an hour before it was scheduled to end -- because he had to return to his church in Philadelphia.

Sullivan said that air bags "should be made optional for all who wish them," but did not say when.

Passive restraints will be required on 1983 mid-size models and on all 1984 models. Automatic belts are now available, as options, only on Rabbits and Chevettes. The belt systems have been circumvented in about 10 percent of these cars, according to a recent survey done for NHTSA by Opinion Research Corp. The list price for the Chevette system is $65. GM charged $225 to $300 for the air bags it offered on certain large 1974 through 1976 models.

DOT Secretary Neil Goldschmidt said he was "personally disappointed" with the GM decision, contrasting it with Mercedes-Benz's.

Ralph Nader, citing GM surveys showing that a majority of its customers strongly prefer air bags even at a cost of up to $360, accused GM of starting a process that "will condemn tens of thousands of Americans to death and injury on the highways every year."

Another angry statement came from NHTSA Administrator Joan Claybrook. She accused GM of "wielding its enormous economic power . . . without regard for consumer choice" and "refusing to commercialize this American invention . . . to save American lives."

GM's Kingman declined to divulge the rationale for the switch from air bags but indicated costs were a factor.

GM "downsized" its large cars starting with the 1977 models, and these were the ones it had in mind when it began tooling up for air bags. But the costs could not be spread out if another downsizing is imminent -- as may be indicated by GM's statement that air bags will be an option on either large- or mid-size 1983 models.