IIn fast-food culture, there may be few things better for your health than preparing a simple home-cooked meal. But while the meal itself may be a good idea, the cooking part can be a problem — at least if you have a natural gas or propane stove. This is the conclusion of a new study in Science Advancesshowing that dangerous levels of nitrogen dioxide (NO2) are emitted by both types of stoves.
The findings are the result of new work conducted at Stanford University by environmental scientist Rob Jackson and researcher Yannai Kashtan. Jackson has been on the trail of the gas stove problem for some time – having co-authored a 2022 article showing that the methane leaking from US residential stoves is equivalent to the emissions from half a million cars per year.
Gas and propane stoves create NO2 when they heat the air so much that two oxygen atoms combine with one nitrogen atom. Electric stoves, which don’t heat up as much, don’t cause the same reaction. NO2 inflames the airways, reduces lung function and worsens coughing and wheezing, according to the American Lung Association. It can be easy to get too much exposure to NO2, as NO2 is not only emitted from stoves, but also from coal power plants It is exhausts.
To study the severity of the NO2 problem generated by stoves, Jackson and Kashtan placed sensors in more than 100 different homes to measure levels of the pollutant after using a gas stove. They took into account many variables: some of the houses were small – just 800 square feet or less; some were large – more than 3,000 square feet. In some cases, the stoves had ventilation or recirculation hoods; in others, no. Other X-factors included the use of more than one burner or also the oven; turn on the stove for minutes or hours; open or close windows; and being in a particular city and ambient air quality. (The study was conducted in seven different cities with different air quality profiles.)
The findings were worrying. For starters, although the kitchen was the first room in a house contaminated by nitrogen dioxide, most other rooms end up being affected as well. “We found that within an hour, concentrations are, in some cases, above health standards in the rooms down the hall,” says Jackson.
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Even when exhaust fans are used, they are not equally effective. In the study, they reduced NO2 levels by between 10% and 70%, depending on whether the exhaust fan is on low or high and whether its opening is large enough to suck emissions from each burner. And that’s just for the most effective exhaust fans – the ones that vent gases to the outside. The kind that recirculates and filters the air and then sends it back to the kitchen does a much worse job.
“They simply suck in the air and spit it back out, passing it through a filter that may never be cleaned,” says Kashtan. “From our work, this appears to do absolutely nothing to reduce concentrations of molecular pollutants.”
The size of a home also makes a big difference, as people who live in smaller apartments or houses experience up to four times more exposure than people who live in larger houses. This not only increases the actual dose of gas consumed, but also the exposure time. The gases “stay above [harmful] limits for hours after the stove is turned off,” says Jackson.
On average, researchers found, gas and propane stoves increase NO2 levels in homes by 4 ppb. That sounds small, but it’s actually quite high, as it takes people about 75% of the way to the World Health Organization’s 5.3 ppb limit, before even taking into account the environmental exposure to NO2 they receive. from cars and other sources of pollution. “They use three-quarters of their allotment, so to speak, without ever leaving the house,” says Jackson.
As with so many other things, race, ethnicity and income play a role here. People of lower socioeconomic status – who tend to live in smaller homes and in communities with more polluted air – experienced twice as much chronic, long-term exposure to NO2 and three times as much acute, short-term exposure compared to people in families richer. earning $150,000 or more per year. The hardest hit groups were Native Americans and Alaska Natives, followed by Hispanics and then black Americans. Asians and white Americans generally had the lowest exposure.
“Poor people breathe dirty air outdoors and, if they have a gas stove, indoors too,” says Jackson. “And that’s not fair.”
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Solving the problem is not always easy. Renters have less freedom than homeowners to switch to an electric stove or install an extractor fan. Even when exhaust fans are installed, many people don’t use them.
“The safest range hoods are big and loud, and that’s not what we want in our kitchens,” says Jackson.
Simpler – and decidedly cheaper – is to buy one or more plug-in electric burners that can be used instead of gas. “You can electrify your kitchen a little and only use gas when necessary,” says Kashtan. Just opening the windows while you’re cooking can also help reduce your overall gas load.
“The risk is cumulative and long-term,” says Kashtan. “I wouldn’t shrug it off and say it’s no big deal, but there are concrete, actionable steps you can take to reduce your exposure.”