Gas stoves not banned, but other appliances targeted

Bay Area air quality regulators voted last week to phase out pollutionchurning furnaces and water heaters that run on natural gas, starting as soon as four years from now.

But the regulators made no reference to gas stoves, which emit many of the same harmful gases that pose risks to human health.

There’s a key reason: The Bay Area Air Quality Management District, which approved the new furnace and water heater rules Wednesday, doesn’t regulate pollution inside homes.

“We do not regulate indoor air quality,” BAAQMD spokesperson Kristine Roselius told The Chronicle.

The agency has jurisdiction over stationary pollution sources that impact outdoor air quality in nine counties surrounding San Francisco Bay. These sources range from oil refineries to residential heaters.

At the state level, the powerful California Air Resources Board, which has led the charge against smog and greenhouse gas pollution, has also left gas stoves alone — even as it approved a plan last year to end the installation of gas-powered water heaters and furnaces statewide in the coming years.

“We don’t have authority on indoor air,” said a spokesperson for the state air board.

Gas water heaters and furnaces, which operate more continuously than stoves, generate higher amounts of pollution over time.

However, the unhealthy gases produced by stoves circulate inside homes — especially those that are not properly ventilated with a range hood — where people breathe them directly.

Gas stoves are “potentially an area where we could make a big difference in exposures,” said Stephanie Holm, a pediatrician at UCSF’s division of occupational, environmental and climate medicine.

But so far, the regulations have not included gas stoves. The BAAQMD’s new rules prohibit new installations or sales of water and space heaters that emit nitrogen oxides (NOx), a group of gases that contribute to neighborhood-level smog and particulate pollution.

It’s a de facto ban on gas-fired heaters because the only ones that currently comply are electric. The rules kick in as early as 2027 for water heaters and 2029 for furnaces.

Last year the California Air Resources Board voted on an overall climate change-and pollution fighting strategy that included a plan to start prohibiting sales of new gas furnaces and water heaters in 2030. The rules are expected to be finalized in 2025.

Gas stoves will likely be phased out in California first in new construction, which is increasingly encouraged or required to be all-electric by regulations in Berkeley, San Francisco, Marin County and numerous other local communities. California Energy Commission standards currently require that new buildings accommodate all-electric appliances, including stoves.

In Southern California, the South Coast Air Quality Management District — which governs a region with 17 million people in parts of Los Angeles, Orange, Riverside and San Bernardino counties — is working on zeroNOx standards for new heating appliances plus cooking appliances that, if approved next year, could be in effect by 2029.

There is clear and bountiful science on the health effects of outdoor pollution. Far fewer studies have examined the risks of gas stoves, but new research links them to childhood asthma.

A study released late last year and published in the International Journal of Environmental Research and Public Health estimated that indoor gas stoves can be linked to 12.7 percent of all incidences of childhood asthma — similar to the proportion blamed on secondhand smoke.

Early this year, a U.S. Consumer Product Safety Commission official told a reporter his agency should look at regulating gas stoves. It set off a firestorm in Washington, D.C.

The agency’s top official issued an explanation, seeking to calm concerns that the government would be racing into people’s homes to claim an appliance beloved by many home cooks.

“Research indicates that emissions from gas stoves can be hazardous,” commission Chairman Alex Hoehn-Saric said, adding, “I am not looking to ban gas stoves and the (commission) has no proceeding to do so.” However, the agency this month issued a request for information on gas stoves, indicating that it was taking a closer look at the health risks associated with them.

Mary Prunicki, a Stanford University expert on the health effects of air pollutants, said an air monitor for particulate matter and volatile organic compounds in her home is triggered when the stove is on but also when her daughter uses hair spray. She said “indoor pollution is just as important as outdoor pollution” when it comes to health hazards.

“You want to remove as many triggers as you can, especially if there are people at risk like small children, the elderly or others with respiratory disorders,” Prunicki said.

In the meantime, people with gas stoves can lessen their risk, according to Holm, who is studying asthma rates among children whose families got rid of their gas stoves in the Central Valley.

Pollution comes off cooking in multiple ways, Holm said. The food itself sends particulate matter into the air. Burning gas emits other substances like NOx, carbon monoxide, methane and benzene.

Ventilating the house — with an open window or, ideally, a range hood — can help clear the air, said Holmes.

“You should always ventilate while you cook,” she said. “If you have a range hood, always, always use it. Turn it on when you start boiling water.”