EMILY KWONG, HOST:
You're listening to SHORT WAVE from NPR.
OK, so in a lot of kitchens, gas stoves sit center stage. Roughly 40% of homes in the U.S. cook with one. And this is after decades of advertising from the gas utility industry.
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UNIDENTIFIED PERSON #1: Ninety-nine percent of the restaurants at the New York World's Fair use gas for cooking.
UNIDENTIFIED PEOPLE: (Rapping) Cooking with gas, Cooking with gas. We all cook better when we're cooking with gas.
UNIDENTIFIED PERSON #2: Natural gas is so great 'cause I can control the temperature really easily.
KWONG: But in recent weeks, these stoves have become kind of a political hot potato.
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KWONG: The U.S. Consumer Product Safety Commission is researching gas emissions from stoves and their associated health risks. And last month, Commissioner Richard Trumka said this before a consumer advocacy group.
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RICHARD TRUMKA: I think we need to be talking about regulating gas stoves, whether that's drastically improving emissions or banning gas stoves entirely.
KWONG: He repeated that clause about banning gas stoves a few weeks later, and it set Twitter alight, as you well know, Jeff Brady. Hello, Jeff.
JEFF BRADY, BYLINE: Yes, I do. Hi, Emily. Yeah, that really launched a big kerfuffle and - fueled mostly by conservative politicians serving red meat to their base and raising money in the process. They piled on with a lot of disinformation. But, you know, what the commission is doing is opening a request for information starting in March. They're researching gas emissions and exploring new ways to address health risks associated with stoves. And the point that Commissioner Trumka was making there is that the Consumer Product Safety Commission should keep all its options open.
KWONG: OK. And as NPR's climate and energy correspondent, you've been following the health and environmental impacts of these stoves for a few years now. The research doesn't look great, I hear. What do we know?
BRADY: A recent peer-reviewed study - it was actually funded by a group that wants people to switch to electric stoves - but it found that 12% of current childhood asthma cases in the U.S. can be attributed to gas stove use. Beyond those findings, Emily, there's 50 years' worth of health studies raising concerns. The federal government has taken note of this in the past, but this time it sounds like officials are taking it more seriously.
KWONG: Jeff, I honestly didn't realize this. This is a big deal. And what about the manufacturers themselves who make gas stoves? Where are they in all of this?
BRADY: Well, the newest thing I've learned is that gas stove manufacturers, they've long known how to make their burners emit fewer pollutants. But they've stuck with the older burner designs instead, even though we know that gas stoves emit these harmful pollutants into your home that can cause or worsen respiratory illnesses, particularly in children.
KWONG: So today on the show, Jeff Brady takes us into the kitchen of an environmental epidemiologist who lights up a gas stove and measures the results.
BRADY: And we'll ask why stove makers who knew how to make cleaner stoves all these years haven't.
KWONG: I'm Emily Kwong.
BRADY: And I'm Jeff Brady.
KWONG: And you're listening to SHORT WAVE, the daily science podcast from NPR.
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KWONG: Now, Jeff, a while back, you stepped into the kitchen with an environmental epidemiologist to measure pollution from a gas stove. You took some of this research into your own hands. Tell me about it.
BRADY: Right. Josiah Kephart is an assistant professor at Drexel University. We tested a gas stove in his Philadelphia row house kitchen.
JOSIAH KEPHART: Well, I'm grabbing a large pot here. I'm just going to fill it up with some water as if I was getting ready to cook some pasta...
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KEPHART: ...Lighting the stove...
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KEPHART: ...And putting the lid on the pot.
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KWONG: Yep. I know these sounds.
BRADY: He then turned the oven on to 375 degrees Fahrenheit, and I turned on a rented air monitor to measure nitrogen dioxide or NO2.
KWONG: And why nitrogen dioxide?
BRADY: Well, it's a toxic gas. And of all the combustion pollutants coming off that blue flame on your gas range, it's the one that most concerns the EPA and other federal agencies because, even in low amounts, nitrogen dioxide can trigger breathing problems for people with asthma and other diseases, like chronic obstructive pulmonary disease. And it's especially a risk for children, which is a concern for Josiah because he has two kids. And research shows children living in a home with a gas stove have a 20% increased risk of developing respiratory illness.
KWONG: That's a notable number. OK. So what happened as the gas stove and the burner heated up and your meter was reading all of it?
BRADY: In less than 15 minutes, nitrogen dioxide levels in the kitchen measured at 168 parts per billion. Now, the hourly guideline from the World Health Organization is 106 parts per billion.
KWONG: Oof, OK. That's, like, 50% higher...
BRADY: It is.
KWONG: ...Than what it should be for safety.
BRADY: It is. That's a significant increase.
KEPHART: If you have kids or if you have any sort of lung condition, this is at a level where, in the literature, in the science, we have seen people start to have these changes in their lungs that could give them worse symptoms or could worsen their disease.
BRADY: There was no vent hood above his stove, you know, to send those emissions outdoors, just an old exhaust fan. It was high up on a wall about six feet away. It didn't work very well. And that's why, after a half an hour, we went upstairs to measure the nitrogen dioxide level in his children's bedrooms, and the monitor read 109 parts per billion.
KWONG: So even a floor away, it was above the WHO safety level.
BRADY: Absolutely. And the longer that stove is on, the more pollution it emits.
KWONG: And I'm thinking about, accumulatively, that exposure, day after day of cooking, to all parts of the house, that would add up.
BRADY: It would. And Josiah says, if you're an adult with a healthy body, you know, and a large hood over a stove that vents outdoors...
KWONG: Yeah.
BRADY: ...These levels are probably not a significant health concern. But for people with asthma, this level of pollution can prompt breathing problems.
KWONG: All right. And how has the gas industry itself - so these are the folks who deliver this fossil fuel to homes - how have they responded to all of this?
BRADY: The American Gas Association says all these claims that cooking with gas causes health problems are unsubstantiated. And making that link is a hard thing for scientists to do. But what's happening is a body of research is getting built up now, and there are gaps still on what we can say for certain. The gas utility industry latches on to that uncertainty and casts doubt over the research that does exist.
KWONG: OK. Sounds like there is an information battle underway.
BRADY: There certainly is. And the gas folks appear to be following a well-worn path that industries, like tobacco, have followed in the past. First, they argue the growing body of science doesn't prove the health concerns. And if that doesn't work, they shift to delaying changes that hurt their business. But there's a twist here because the industry itself actually developed ways to make cleaner gas stoves already. There was this time in history where cleaner gas stoves could have been made.
KWONG: Excuse me? What? When?
BRADY: So this was back in the 1980s. The Consumer Product Safety Commission was looking at kerosene heaters. These were - you put it in your living room to heat your living room.
KWONG: Yeah.
BRADY: And they were thinking about banning these because of the pollution they emitted into homes. Gas utilities saw that and worried the commission would come for stoves next. So they started researching how to make cleaner burners on those gas stoves. One that was developed is an infrared burner. It uses 40% less gas and emits 40% less nitrogen dioxide. But appliance manufacturers have never offered that for sale.
KWONG: Why?
BRADY: There are a few downsides. These burners were more expensive to make. They're more fragile, and they didn't have the blue flame that's a big part of the gas industry's marketing. But more importantly, you know, customers just weren't demanding cleaner gas stoves from manufacturers at that time. So they didn't make them.
KWONG: So there wasn't a business incentive...
BRADY: Exactly.
KWONG: ...To make them.
BRADY: Exactly.
KWONG: Let's put a pause on air quality. I want to talk about climate change itself, because, right, clearly, these gas stoves, they emit indoor air pollution. But what about outdoors? What effect is this having on greenhouse gases?
BRADY: That's a significant issue because these gas stoves, they leak methane into the environment even when they're turned off.
KWONG: Really?
BRADY: Yeah. So natural gas is made of methane, a super potent greenhouse gas. And methane, it just wants to leak.
KWONG: I mean, that's what gases do.
BRADY: Of course. They want to escape. And gas stoves are connected to this vast system of pipelines and compressor stations, fracking operations, wells. Anywhere along that production line that there's a connection, there's a chance for a leak. And the industry has reduced a lot of what they call fugitive emissions in recent years, but they haven't eliminated them. And now inside the house, scientists at Stanford University measured methane emissions from gas stoves in 53 California homes. They found that most leaks happened when the stove was off and were caused by loose couplings and fittings.
KWONG: OK. So parts of the gas lines and pipes were loose?
BRADY: Exactly. Now here's Rob Jackson. He was one of the study's authors.
ROB JACKSON: Simply owning a natural gas stove and having natural gas pipes and fittings in your home leads to more emissions over 24 hours than the amount emitted while the burners are on.
BRADY: And he said it didn't matter if the stove was old or new or even what brand it is.
KWONG: OK. And do we know what impact all of this is having on climate change in the U.S.?
BRADY: Yeah. Researchers estimate a little over 1% of gas used in stoves leaks into the atmosphere. And that might not sound like very much, but if you add up all the stoves - there are about 40 million in the U.S. - Jackson estimated the amount of methane leaked every year has about the same climate change effect as the carbon dioxide from a half million gasoline-powered cars. And that's a problem. Scientists say that to avoid the worst consequences of climate change, of course, most of the world's fossil fuels, they just need to stay in the ground.
KWONG: Interesting comparison, because with cars, you know, there's this movement to convert to electric that's really taken off. Is the same thing happening in the gas utility sector?
BRADY: You know, honestly, no. This is really just an existential threat for gas utilities because climate-focused energy modelers say that it's really hard to find a cost-effective way to reach net-zero emissions if gas is still getting burned in individual homes and offices. So those utilities are trying to find cleaner replacements, things like so-called renewable natural gas from agriculture and landfills, then mixing in hydrogen that's produced with renewable energy. When I think about this, there's a quote - it's almost two years ago now that she told me this - from American Gas Association president and CEO Karen Harbert. And this really sticks with me.
KAREN HARBERT: If the goal is to reduce emissions, we're all in. If the goal is to put us out of business, not so much.
BRADY: So gas utilities are getting laws passed to preserve their business. Twenty states now have laws on the books. And these laws, they prevent cities from banning gas hookups in new buildings. Still, the number of communities choosing to ban new gas hookups and encourage their residents to switch from gas to electric is growing.
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KWONG: Jeff Brady, climate and energy correspondent for NPR, thank you so much for coming on the show.
BRADY: Well, and thank you so much for having me. This was fun.
KWONG: If you have a science question about gas stoves or any other appliance in your house, send us an email. Our address is shortwave@npr.org. Today's episode was produced by Margaret Cirino, edited by supervising producer Rebecca Ramirez and fact-checked by Anil Oza. Brendan Crump is our podcast coordinator. Our senior director of programming is Beth Donovan, and the senior vice president of programming is Anya Grundmann. I'm Emily Kwong. Thank you so much for listening to SHORT WAVE, the daily science podcast from NPR.
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