When momentum starts to build, people like to exclaim, “Now we’re cooking with gas!” Well, a recent study out of Stanford University might have us re-thinking that expression. The study found that methane leaking from stoves inside U.S. homes has the same climate impact as about half a million gasoline-powered cars and, furthermore, that these stoves expose household members to respiratory disease-triggering pollutants. Findings like these are prompting some jurisdictions, like the US’s largest urban center, New York City, to ban gas hook-ups in new buildings. Keep in mind that approximately 2000 new buildings are erected there each year. This week on Sea Change Radio, we speak with Eric Lebel, part of the Stanford research team that conducted the study, to learn more about their methods and findings. We discuss the impact that America’s 40 million gas stoves might be having on the air we breathe (both inside and out of our homes), how to transition away from these types of appliances, and why in many ways it’s an environmental justice issue.
Narrator 0:01 This is Sea Change Radio covering the shift to sustainability, I’m Alex Wise
Eric Lebel 0:25 The big take home message I would like people to take away from this study is that it’s the gas stove is when considering its impact. It’s not just a climate impact. It’s not just a health impact, but it’s really the two together and I hope the narrative around the gas bands will be able to use these data in tandem with each other to advance the narrative that the gas stoves are both a hazard to climate and to health.
Narrator 0:50 When momentum starts to build, people like to exclaim, now we’re cooking with gas. Well, a recent study out of Stanford University might have us rethinking that expression. The study found that methane leaking from stoves inside us homes have the same climate impact as about a half a million gasoline powered cars. And furthermore, that these stoves exposed household members to respiratory disease triggering pollutants. Findings like these are prompting some jurisdictions like the US is largest urban center New York City to ban gas hookups in new buildings. Keep in mind that approximately 2000 new buildings are erected there each year. This week on Sea Change Radio, we speak with Eric Lebel, part of the Stanford research team that conducted the study. To learn more about their methods and findings. We discussed the impact that America’s 40 million gas stoves might be having on the air we breathe, both inside and out of our homes, how to transition away from these types of appliances, and why in many ways, it’s an environmental justice issue.
Alex Wise 2:19 I’m joined now on Sea Change Radio by Eric Lebel. He’s a senior scientist at PSE healthy energy in Oakland. And as a graduate student, he worked on the Stanford gas stove project. Eric, welcome to Sea Change Radio.
Eric Lebel Thank you for having me, Alex.
Alex Wise So I wanted to talk to you about the research that’s been in the news recently about gas stoves and ovens and the methane and gas released that accompanies these appliances. Why don’t you first kind of take a step back and tell us about what piqued your scientific curiosity as a collective?
Eric Lebel 3:07 Sure. So this project started as part of a larger project looking at methane emissions from home appliances. And looking at the methane emissions that are leaked from natural gas appliances in homes. And one of the reasons why scientists are interested in methane emissions from homes is that as a potential source of methane emissions, especially in urban environments, where they haven’t been calculated and quantified. In certain areas, there was a paper in 2015 that came out in Boston, for instance, that showed that there was a big gap in emissions when you try and total the sources of methane emissions from sources in the city. So like leaks from distribution pipelines, etc, and then looking at methane emissions from the city overall. And so one of the hypotheses there was that a lot of the methane was coming from buildings, and specifically appliance leaks into buildings, incomplete combustion from methane as it’s being burned in appliances, and maybe even leaks from meters and the pipes within the building themselves. And so one of the things we we looked at was, was, this is actually the second paper on that we’ve published on this topic. The first was looking at the difference in methane emissions between tankless and storage water heaters. And so we did a similar project there were we quantified the emissions from from tankless and storage water heaters and then have now moved on to looking at methane emissions from from gas stoves. If you can give kind of a executive summary of the findings of the gas stove paper, that would be terrific. What you found was that the emissions of methane from gas stoves actually mostly come from while the stove is off. So even while your stove is off, it’s still emitting a small quantity of methane.
Alex Wise 4:49 And in total, the methane emissions from gas stoves on a terms of the climate impact are about the same as the carbon dioxide emissions from about half a million cars in the US.
Eric Lebel 5:04 And so one of the things that we’ve we found was that even these small leaks of methane that we’re finding from stoves, even while they’re off, they do add up to substantial climate impacts. And can you break down the methodology that you use to quantify the emissions? Sure. So what we did was we enclose the stove with a plastic around this around the stove to be able to capture all the emissions in the stove. So the way this plastic works is, I don’t know if you’ve ever walked through a mall or an airport, and they’re doing construction at a certain section of that area. And they’ve blocked off the area with plastic sheeting to keep the Dustin using tension rods. And so we did something similar in kitchens where we had tension rise, and we hung plastic, you know, about maybe several feet back from the stove. So it’s not right up against the stove, but it’s several feet back, and able to contain the emissions in a known area of space. And we were able to quantify the volume of of in this space and quantify how tight of a seal we’re able to make, and then turn the stove on and use it like normal inside the space and quantify how the changes in concentration would translate into emission rates from the stove. And through this, we were able to quantify just how much the stove was emitting while it was off while I was on and then while it was turning on and off, you know, when you turn your stove on, it makes the click click click sound. And sometimes you could smell a little bit of gas. Well, we were able to quantify just how much gas comes out during that time.
Alex Wise And surprisingly, you discovered that three quarters of the emissions come from when the stove is off, is that correct?
Eric Lebel That’s right, when you take into account also how much people use their stoves over the course of a given day or week, we’re able to calculate that even though the stove is off most of the time, those small emissions that are being we’ve found while the stove is off, and add up in total to being three quarters of the total emissions from the stove. Now obviously wanted to isolate the space, as you mentioned, to quantify just the emissions coming from gas stoves. But when we look at how harmful those emissions are, how would you then extrapolate that into a larger space? I’m thinking most notably here in California, we’ve been having pretty extended fire seasons, and we have we’re all checking the air quality. And so we’re aware of whether the air is bad outside, but a lot of us aren’t really considering that it might be bad inside as well. How do gas stoves and ovens play a role in the new bad air? If you will? Yeah, that makes a lot of sense to really do need to start thinking more about indoor air quality as well. I will say that the methane emissions that come from the stove are not contributing to indoor air quality. So we’re not concerned we’re concerned about the methane emissions in terms of their climate impact. What we are concerned about when we think about how gas stoves contribute to indoor air quality is the byproducts of emissions from the stoves. So what we measured specifically in this study are emissions of NOx or nitrogen oxides, which is made up of NO NO to nitric oxide, nitrogen dioxide, and nitrogen dioxide is a respiratory irritant and cause coughing, wheezing, asthma are especially prone in children. And this is a direct byproduct of the combustion of the gas stove. So we did measure this and as part of this study, but stoves are also known to emit carbon monoxide, and particulate matter and formaldehyde potentially. So these are other things that that could be measured in the future as well. So the methane is not the primary concern from a health standpoint in the house, that’s more of a environmental hazard. Is that correct? That’s right. The one thing you we are concerned about with methane at least is is also the safety component of it. Methane is explosive at about 5% concentration. And so that’s why the gas companies will put in mercaptans and the gas the sulfur compounds that give it the rotten egg smell. So that’s that’s an additive to the gas on its own, you wouldn’t be able to smell or sense that methane was being emitted from the stove but the mercaptans and then make it smell so that when when it does leak, you are able to detect it with your nose. So the if you do smell leak, it’s definitely very important to get that checked out. It’s just because it could be a common safety hazard for in case it does explode if there’s an ignition source where the concentrations really high. But in our study the concentrate that we were finding where we’re not that high. We couldn’t smell them in most cases, although some we could we could detect. And the and from that perspective, it’s mostly a climate concern at that point. We’re concerned about methane emissions, even small emissions of methane just because methane is such a strong greenhouse gas over the course of the 20 year timescale, the same weight of methane pound for pound it’s 86 times stronger than carbon dioxide as a greenhouse gas.
Alex Wise 11:42 This is Alex Wise on Sea Change Radio and I’m speaking to Eric Lebel. He is a senior scientist at PSE healthy energy in Oakland and he was a member of the Stanford University gas stove project. How has the industry changed in terms of the makeup of our kitchens in terms of gas? And then have the new appliances become safer or not?
Eric Lebel 12:39 Yeah, so currently, there’s two reported there’s just over 40 million gas stoves in the US. So about one in three households have a gas stove. Not everybody who has a gas connection to their house has a gas stove. And a lot of people will also have propane, or other types of sources of gas. But yeah, so all this changed in the last few years. The big thing that’s changed is that the old wedge woods that you were referencing are mostly pilot-light ignition sources. So there’s a little tiny flame in the stove that stays on the whole time. And that’s the ignition source for when you want to light a burner. But most modern stoves that have been produced in the last several years have ignition or electronic ignition sources so that they have a little sparker at the clicking sound that you hear when you turn the burner on. And so that eliminates the need for that that small pilot light and in the stove. And the study that we did, we didn’t measure as many of the pilot light stoves are not as common anymore anyway. But it’s definitely something that we’d want to look at in the future to is just with a larger sample size is looking at how the technology has changed in the last, you know, several years and how that influences the emission rates from the stoves we only measured two out of the 53 stoves were pilot lights, just because of not being able to get access to them did the to stand out as particularly worse or is that inconclusive just because of a smaller sample size. Yeah, it is inconclusive because of the small sample size, but one of them did have high emissions, we don’t know if we can contribute attribute that to the pilot light specifically or just because it was an old stove. But there was one that that did have higher than the one that went that had a lot of emissions, what did have a pilot light. But another thing that we want to think about as well, too is that it is a small sample size. And overall we didn’t see any trends in an age of the appliance or the brand of the appliance. And a lot of that could also just be because because it is such a small sample size. And it does warrant future research and, and going forward. Because these are indoor appliances.
Alex Wise 14:00 They don’t fall under the purview of the EPA. I was surprised to hear is that correct? \
Eric Lebel Yeah, so technically the EPA only publishes standards of for no two specifically for outdoor air. And the one our standard for outdoor air is 100 parts per billion. And so we use that anyway for our indoor samples for the gas stoves just as a benchmark. And one of the things that we found was that the gas stoves emit nitrogen dioxide From the gas burners in proportion to the amount of gas that they use, so the more burners you have on, if you turn a burner on higher or use a bigger burner, you’ll get more nitrogen dioxide being emitted from your stove. And interestingly, a lot of people have access to a gas vent or the stove vent above the the stove. But for about a quarter to a third of people, they don’t use it either, just for different reasons. This is something that other people have published in different studies. And, and we found in our study that if you have, and particularly in places where there’s a small kitchen size, and the gas vent isn’t on and it’s it’s not very much other ventilation going on in the kitchen, that it’s very possible to exceed that 100 parts per billion outdoor standard in your kitchen just by using your burners and your oven. Looking at it from a more holistic standpoint, and from the human body, inhaling these gases, if you were going to like kind of connect the dots from an epidemiological standpoint, how would you go about assessing the risk that these ovens pose? Yeah, this is definitely a need for future research. And the California Energy Commission is putting out some money for researchers to do this study in the next couple of years. Where they’ll compare the difference between gas stoves and, and electric stoves and and how the occupants health respond to that, and specifically looking at asthma outcomes and, and other other health outcomes. But yeah, this is something that that’s for now, we don’t really know much about this topic. And we definitely do need to know more about the source attribution, as you say that the wildfires are definitely decreasing the air quality in California and outdoor air quality is decreasing. How can we also attribute, you know, the health or responses to the change in air quality to, you know, possible indoor air quality sources. And our work has just simply identified that the gas stoves are a potential source for nitrogen dioxide. And we have a better idea of just how much gas they’re emitting now. And we can come up with ways to try and reduce the effect of that on on the occupants. And one of the easiest things that people can do right now is just anytime your burners on no matter if you’re, you know, cooking something or even just boiling water, it’s always good to turn your gas vent on, if you have one, even with if the anytime the burners on.
Alex Wise 17:40 And thinking of the ventilation issues at the outset of our conversation, you mentioned how this is in many ways an environmental equity issue, why don’t you expand on that if you can?
Eric Lebel Yeah, for sure. It’s definitely an environmental equity issue. One of the things that causes these higher concentrations in homes is kitchens that may be smaller or tighter or don’t have as good ventilation system. And typically, you know, people and disadvantaged communities are the ones who have the smaller kitchens and the stove, it’s on more frequently, or the poor ventilation systems above the stove. And so it’s definitely important to think about that, as we go forward to and just how can we can we better address these communities and address this environmental justice issue? Yes, I mean, if you don’t own your own home, you may not have a lot of leverage to ask your landlord to switch out your stove for you. Is that kind of the basis of it? Or is it more that the people who have guests, those who are in the lower income brackets may not have good ventilation for these appliances? Yeah, I would say it’s a combination of all that, that you bring up the renter issue. And that’s, it’s another interesting component to think about is that a lot of people don’t have the, as now at their disposal to make a decision to change out their gas stove, if they don’t own the house and their landlord owns it. The landlord doesn’t necessarily have any incentive to change out the gas stove just for, you know, if there’s no financial incentive for them, there’s no incentive for health and because they don’t live in the house. So yeah, it’s definitely something to think about, and how can we, we address these issues, especially for those who may be renting as well. But yeah, the big component to is just as the thing that drives the the the concentrations inside the kitchen, er, there’s basically three things that go into is how much NOx is being emitted by the stove, which we measured. And then the concentrations are dependent on what how big the kitchen is, and then secondly, how much ventilation there is in the kitchen. So that could be things like if your windows open, or if your exhaust hood is on, or if you have internal H HVAC system that’s somehow able to circulate the air within the house that’ll be able to decrease the local concentrations of these pollutants in your kitchen while you’re cooking.
Alex Wise Or if you’re eating a higher percentage of your meals at home cooking more.
Eric Lebel Exactly right yeah cooking for more people inside your house for instance
Music Break 20:21
Alex Wise 21:25 This is Alex Wise on Sea Change Radio. And I’m speaking to Eric Lebel. He is a senior scientist at PSE healthy energy in Oakland. So anybody who works on a project that pops holes in the fossil fuel industry has to be prepared for the inevitable pushback from that industry. And I’m sure you’ve read some of the criticisms of of the study that you and your colleagues at Stanford were involved in, I read one in the Washington Post piece that I saw, I forget the gentleman’s name, but he was an industry spokesperson. And he kind of dismissed your study as this was just measuring them in plastic. And that’s not a real world application. Obviously, this is a peer reviewed study. So the thing to remember is that the point of this study was to measure the rates of emissions from stoves, and not to measure the local concentrations inside the kitchen.
Eric Lebel 22:01 So for the methane emissions, no one, we don’t care as much about indoor air concentration, as long as it’s below that safety threshold we discussed earlier. And in every case that we measured here that we were well below that safety threshold, we’re talking single to double digit parts per million methane concentrations inside the kitchen, when the explosive limit is 50,000 parts per million. But what we are able to quantify using the plastic method is the the rate of emissions. So now we know just how much gas is being emitted from the stove during different phases of operation, and then we can turn that into a total quantity of emissions. With the NOx emissions, however, we we also are we’re interested in measuring the rates of emissions from the from NOx within a kitchen environment from a stove. But we weren’t necessarily, we wanted to measure the rates of the emissions so that we could use those numbers for other indoor air quality modeling. So now we can say beyond the 53 stoves that we measured if you have a stove and and this kitchen that’s this size with this ventilation. And it’s used this much per day, we can calculate what the expected concentrations would be, you know, with without the exhaust hood fan, without with different cooking patterns, etc. And then we could use that to better quantify the health risks of of using a stove in in these environments. I will say that we did measure a couple kitchens without plastic. And just because we were in an apartment that was a reasonably sized that we could we could measure the the emissions and by changing the change in concentration directly in the kitchen and living room environments. And even in these environments, just by turning the stove and oven on, we were still able to exceed that 100 parts per billion threshold for no two, even though we didn’t have the plastic and we weren’t using that in those situations.
Alex Wise 24:00 And another position that was implied by a spokesman in this piece that I read was that this is an agenda driven study that wants to electrify the American appliances that seemed a little far-fetched to me, but maybe you can explain the funding behind your study. And if there is any connection between the electric oven industry and the Stanford graduate group that worked on this project. Yes. So the funding for this project just came from Stanford research grants. We the agenda of this project was to quantify methane emissions from natural gas stoves and particularly during each of the phases of operation we there was no internal agenda to for electrification or the electric stove industry did not underwrite this.
Eric Lebel 25:00 That is correct. There is no underwriting from the electric stove industry. Now this would probably be a separate study, but I was thinking of the environmental study that I would like to see for industrial size stoves and thinking of cooks, chefs who are working kitchen workers who are exposed to these much larger gas ranges. That probably wasn’t a piece of this study wasn’t no, we didn’t look at any commercial kitchens. But it’s definitely something I’d be interested in looking at as well in the future. Typically, on commercial kitchens, especially with health impacts, even though they have those much bigger burners, and there’s more of them being used simultaneously. They typically have higher air change rates than a house in a commercial building. And I, my understanding is, is that their exhaust hoods are much more powerful as well than you would get in a residential home. So that’ll help decrease the concentrations of pollutants coming off the stove.
Alex Wise 26:04 So obviously, this took a long time to produce this paper and the work that you and your colleagues did, what do you hope people around the country take away from it in terms of not only their own health, but in terms of methane use and methane emissions and the natural gas industry as a whole?
Eric Lebel 26:35 Yeah, so I think one of the things that this study is is important for is that it it packages together the climate and health impacts of having a natural gas stove. So we know, we’ve known that methane is a greenhouse gas and is damaging the climate. Now we have an idea of how much gas is being emitted from the stove, especially while it’s off. We also know that natural gas stoves have the potential to increase concentrations within homes to above EPA thresholds for nitrogen dioxide, for instance, and potentially for other compounds as well, which will hopefully be able to measure some more of in the future. So I think that the the big take home message I would like people to take away from from this study is that it’s the gas stove is when considering its impact. It’s not just a climate impact. It’s not just a health impact, but it’s really the two together and I hope the narrative around the gas bands will be able to use these data in tandem with each other to advance the narrative. That is the gas stoves are both a hazard to climate and to health.
Alex Wise He’s a senior scientist at PSE Healthy Energy in Oakland, Eric Lebel. Eric, thanks so much for being my guest on Sea Change Radio.
Eric Lebel Thank you for having me, Alex, this was great.
Narrator 27:46 you’ve been listening to Sea Change Radio. Our intro music is by Sanford Lewis and our outro music is by Alex Wise. Additional music by Willie Bobo, Buckwheat Zydeco and Sonny Terry. Check out our website at SeaChangeRadio.com to stream or download the show or subscribe to our podcast. Visit our archives there to hear from Bill McKibben, Van Jones, Paul Hawken, and many others. And tune in to Sea Change Radio next week. As we continue making connections for sustainability. For Sea Change Radio, I’m Alex Wise.