Gas stoves favored by cooks give off so much methane across the United States — most when the appliances aren’t even in use — that they have the same impact on our atmosphere as half a million cars.
Stanford researchers analyzed indoor levels of heat-trapping methane and nitrous oxides – pollutants that can trigger asthma and other respiratory problems – and found surprising amounts of each seeping from stoves. The study, released Thursday, comes as communities nationwide debate whether to ban the use of natural gas in new buildings as part of the fight against climate change, and the gas industry is mobilizing to block these bans.
“Gas stoves heat the planet and release pollutants from the indoor air you breathe — you get both,” lead author Rob Jackson, an environmental scientist at Stanford, said in an interview. Eliminating gas service for newly built homes makes sense, he said, “otherwise we lock in greenhouse gas emissions for decades to come.”
Methane, the main component of natural gas, has more than 80 times the global warming potential of carbon dioxide for the first 20 years after it is released into the atmosphere. The study, which measured methane levels in 53 California home kitchens sealed with plastic sheeting, found that both old and new stoves leak gas, with 76% of emissions occurring when appliances are not in use. Since more than a third of US households, or 40 million homes, have gas stoves, researchers estimate that their national methane emissions each year have the same global warming potential as about 500,000 cars.
The study also looked at nitrous oxide levels in 32 of the kitchens and found that during stove use, pollutant levels can exceed federal exposure guidelines if the kitchens don’t have ventilation hoods. or if these hoods are not on. The amount of methane from leaking pipes and fittings, incomplete gas combustion, stove design features, or a combination of these factors is unclear.
The researchers would like to expand the study to include more homes and stoves, as the pandemic has limited testing. The tests involved sealing off part of each kitchen to prevent emissions from gas ovens or water heaters elsewhere in the house. The researchers worked with real estate agents to find empty homes or rented them out on Airbnb. The study included 18 stove brands, ranging in age from 3 to 30 years.
“The trickiest question is how to swap old stoves,” Jackson said. “I hope for all readers that their next stove will be electric, no matter when they buy it.”