SAN FRANCISCO—Oil refineries will have to cut the air pollution they generate while burning gases under a groundbreaking rule approved by smog regulators.

The rule, which the Bay Area Air Quality Management District adopted Wednesday, is the first of its kind in the nation. Air quality officials throughout the country are closely monitoring it, and regulators in Southern California aim to impose similar restrictions later this year.

Community groups in Richmond had long complained about flares, which occur when refineries burn excess gases. Air quality officials found that flaring spewed out eight tons of pollution a day, including six tons of volatile organic compounds, which contribute to smog.

Under the new Bay Area rule, refineries can let off flares only for safety reasons. Violators will have to file reports explaining why they exceed limits.

“Flares are an important safety-control device when refineries have excess gases” that they must burn off to avoid explosions, said Jack Broadbent, the chief executive officer of the Bay Area district. “But we had a situation where refineries were relying on flares as a routine way of running the facility.”

In the Los Angeles region, the South Coast Air Quality Management District began monitoring flaring in response to complaints about the practice at refineries in coastal communities south of Los Angeles. Flaring emissions turned out to be worse than suspected.

South Coast officials intend to impose new rules this fall capping the excess emissions and fining violating refineries.

“We are going to develop a rule that has a little more teeth” than the one approved by the Bay Area district, said Laki Tisopulos, assistant deputy executive officer in charge of new rules for the South Coast district.

Refineries have tried to cut flaring since air quality agencies began monitoring the practice. In the Bay Area, emissions have plummeted 75 percent, and in the Los Angeles region, 70 percent.

Joe Sparano, president of the Western States Petroleum Association, said these reductions show that the regulations are unnecessary. He said, however, that the oil industry wouldn’t object to them as long as flaring is allowed to avoid safety problems and refinery shutdowns, which could further inflate the state’s gasoline prices.