- A recent study has found that gas stoves are constantly leaking methane, a potent greenhouse gas, even when they’re turned off.
- Burning methane also produces nitrogen oxide, a gas that can exacerbate respiratory ailments.
- To keep your family safe, always use a hood vent. And when it’s time for a new stove, consider an induction cooktop, which uses an electromagnetic current to heat pans.
Heads up to the 40 million American households with gas stoves: your appliance is constantly leaking methane, a potent greenhouse gas, even when it’s turned off.
That’s according to a new study published late last month in Environmental Science & Technology. Researchers from Stanford University found that even when gas stoves aren’t running, they release 2.6 million tons of methane into the air each year, a figure on par with the amount of greenhouse gas that 500,000 cars release annually.
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Beyond contributing to global warming, the study also found that gas ranges emit unhealthy levels of nitrogen oxide, a gas the Environmental Protection Agency (EPA) says can trigger breathing problems for people with asthma or chronic obstructive pulmonary disease, even in low concentrations (which the World Health Organization defines as 13 parts per billion over 24 hours).
While natural gas leaks from wells, plants, and pipes have been studied extensively, relatively little research has been done on leaks inside the home. “It’s probably the part of natural gas emissions we understand the least about, and it can have a big impact on both climate and indoor air quality,” Eric Lebel, lead author of the new study, says in a Stanford press release. Lebel is a senior scientist at PSE Energy, a nonprofit based in Oakland, California.
Lebel and his fellow researchers spent time in 53 homes (mostly rentals and Airbnb’s), sealing off the kitchens with plastic sheets and measuring the methane and nitrogen oxide that the stoves released. The team took measurements while the appliances were turned on and while they were turned off, something previous studies had not done. The stoves ran the gamut from three to 30 years old and represented 18 different brands, including major names like GE, Whirlpool, and Frigidaire.
The leakiest stoves were the ones that utilized a pilot light—a small, constant flame used as an ignition source for gas-powered appliances. Most newer ranges have done away with pilot lights because they waste gas; instead, they use a built-in electric sparker that, when gas is added, creates a flame.
Regardless of age or brand, methane was released into the air during ignition and extinguishment, about the same amount of methane emitted during ten minutes’ worth of cooking with the burner. Shockingly, more than three-quarters of methane emissions occurred when the stoves were turned off. Using this data, the researchers were able to determine that 1.3 percent of the gas that the stoves use is leaked. This suggests that gas fittings and connections to the stove play the largest role in the escape of natural gas, according to Lebel. These include gas valves at the burner and where the gas supply enters the appliance from the wall.
While carbon dioxide is the focus of most conversations around climate change, methane is a significant contributor to global warming. And while it doesn’t linger in the atmosphere as long as carbon dioxide, methane’s heat-trapping power is 25 times more potent, meaning it can cause more warming in less time. During the last 200 years, humans have more than doubled methane concentrations in the atmosphere (through industry and agriculture), which has led to steadily increasing temperatures.
The study did not attempt to pinpoint the specific source of the leaks, though Zachary Merrin—a research engineer at the Illinois Applied Research Institute’s Indoor Climate Research and Training Program, who was not involved in the study—hazarded a guess. “I would not be surprised if some of the leakage is coming from the burner valves at the stove controls,” he wrote in an email to Popular Mechanics. “These valves need to hold back pressurized gas but allow it to open with the flick of a wrist; I would imagine it is hard to mass produce these valves so that they maintain a perfect seal for the lifetime of the device.”
Thankfully, the levels of methane that the researchers found in the homes are not dangerous to humans and won’t cause explosions—but exposure to nitrogen oxide, a byproduct of burning methane, can worsen significant health problems. During the tests, the researchers detected levels of nitrogen oxide above 100 parts per billion, which exceeds the EPA’s outdoor air quality standards (it does not have indoor standards), within minutes of turning on the stove. The concentration of this toxic gas increased in proportion to how many burners were used and for how long; it was most pronounced in small kitchens and those with poor ventilation.
In recent years, states and local governments have begun banning natural gas connections in new construction, but the natural gas industry isn’t going down without a fight. It has spent many years (and a lot of money) convincing Americans that gas stoves are superior to electric (this outreach has traditionally taken some truly odd forms, from tapping social media influencers to an astoundingly bad 80s “rap” video) and has recently been successful in lobbying for legislation against these new bans.
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Meanwhile, the Washington, D.C.-based American Gas Association (AGA) has taken issue with some of the study’s findings, arguing that wrapping a kitchen in plastic is “in-no-way a realistic measure of the circumstances in a typical home,” and questioning the accuracy of taking “data from 53 houses in California and extrapolat[ing] it to the entire United States.” Furthermore, the group alleges that the situation is actually improving.
“Residential natural gas accounts for only four percent of total U.S. greenhouse gas emissions, and natural gas distribution system emissions have declined 69 percent since 1990,” AGA President and CEO Karen Harbert tells Popular Mechanics through a spokesperson. Harbert claims the group is spending $30 billion each year to modernize the country’s natural gas system.
But what does this all mean for the average homeowner who, for now, is stuck with—or even prefers—their gas stove?
“We don’t want people to go out and completely ditch a perfectly good gas stove,” Lebel tells Popular Mechanics. “Running out and replacing your stove is not the right response at this time.” In other words, a pile of working appliances in a landfill is not an environmentally friendly solution.
Homeowners can protect their health by following one simple rule: “Any time there is a burner on, your vent should be on.” If possible, make sure your hood (or microwave fan) is pushing the air outside, not simply recirculating it. If all else fails, open a nearby window to promote ventilation.
“To help your stove perform better,” Merrin advises homeowners “keep the surface and the burners clean, making sure the burner caps are centered and well-seated, and fixing any issues with the igniters if the stove is not lighting quickly or completely.” Steady blue flames, he explains, indicate the stove is working well. “If the flames show a lot of orange or sound like they are gusting, it means that the air fuel mixture is not optimal and excessive incomplete combustion is occurring, which increases the generation of harmful pollutants.” Renters can also protect their health by keeping their stove clean and requesting their landlord provide proper maintenance.
Lebel says he is unaware of any manufacturer efforts to address leaky appliances, and neither GE nor Samsung responded to requests for an interview.
When it is time to replace your stove, consider an electric induction cooktop. While electric stoves have their drawbacks (namely, burning fossil fuels to generate power) induction stoves use an electromagnetic current to heat pans and their contents quickly and evenly without producing excess heat, dangerous flames, or harmful pollutants.
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