Tracking The Toxic Fallout Of The LA Fires

FLORA LICHTMAN: Hey, it’s Flora Lichtman. And this is Science Friday. Today on the show, the toxic fallout of urban fires. This time last year, Los Angeles was on fire. More than 16,000 homes and buildings burned to the ground. Cars, batteries, solar panels, insulation, cleaning supplies all up in flames, releasing toxic chemicals into giant smoke plumes that wafted across the city. A year later, scientists are trying to understand the fallout from this urban wildfire, what chemicals were left behind, how to remediate them, and what threats they pose to our health.

My next two guests have been at the forefront of this research. And for one of them, this work is personal. Dr. François Tissot is a geochemist at Caltech. And Dr. Yifang Zhu studies air quality and its health effects at UCLA. Welcome to you both to Science Friday.

YIFANG ZHU: Thank you for having me.

FRANÇOIS TISSOT: Thank you.

FLORA LICHTMAN: I want to get into the toxicology in a second. But, François, let’s start with your personal story. What happened in your neighborhood?

FRANÇOIS TISSOT: Yes, well, our neighborhood was almost completely burnt down. Our streets, only the house that we used to live in and another one didn’t burn. Everything around is just complete desolation. The house is so contaminated with heavy metals and asbestos. And it’s completely unlivable and unsafe.

FLORA LICHTMAN: I mean, obviously, this is so personal, but you also made it professional. Why?

FRANÇOIS TISSOT: Well, we made it professional because we have the tools to make a difference and bring data that was missing. I guess the first thing I did when I saw that the fire was happening is, I looked up if there was any paper that we’re discussing, how much lead and heavy metals and contaminants will be transported, and how far and what are the risks I wanted to understand. But it turns out there is almost no literature on this kind of urban megafires. There are new kind of threats. There is very little that is being known. And there was nothing for me to make an assessment of risk from.

So I told my group that if anyone in the group wanted to work on this, we should really do it. And the response was very positive from them. And we got started immediately trying to answer very basic questions, such as the lead that had been seen in the air, how far did it go, how much was released, how much of a danger to human health is it.

FLORA LICHTMAN: What do you usually work on?

FRANÇOIS TISSOT: My training is in a field called cosmochemistry and geochemistry, which is the study of planetary formation and solar system evolution using meteorites and chemical tools. Typically, we make very complex isotopic measurements, very precise measurements. Concentration measurements are much simpler for us. They’re usually the step one of anything we do. And except in this case where the fire concentrations are all you need to know, because you just want to know if the element is present in what quantity, so that you can assess how big of a risk it is.

FLORA LICHTMAN: I mean, you must have felt desperate, in some way, to get these answers.

FRANÇOIS TISSOT: I was really shocked to see that there had been no systematic studies until now. Because urban fires are not a complete novelty. But I guess the magnitude and the scale of the devastation that those mega fires bring, this is novel. It has not been studied. And so, well, I guess we were at the wrong place at the right time to make a difference.

FLORA LICHTMAN: Yifang, I know you have been collecting samples and testing the air for the last year. What have you found?

YIFANG ZHU: Yeah, so we took three phases of measurements, right? We collected air samples during the active fire period, and then went back again and take measurements when the fire was about halfway contained, and then went out again another round to take air samples when the fire was completely put off. So when we take measurements, we collect samples inside and outside people’s homes, both indoors and outdoors. I think the big surprise to us is how much higher some of those chemicals were inside homes, compared to outside after the fires were over.

So this is especially true in homes where no one was living at the time. So we know there’s lots of indoor sources. Cleaning products, cooking, smoking all can produce those VOCs inside people’s homes. But the fact that we’re seeing those high levels inside homes that is unoccupied really tells us there’s some source going on in those homes. So this is really an important public health message, basically, saying that people really need to be aware about potential exposure and risk when they’re considering returning homes.

FLORA LICHTMAN: When you say inside, was it air quality? Was it your sofa was loaded with these toxic chemicals? What do you mean?

YIFANG ZHU: Yeah, that’s a very good question. We actually did two parallel projects where we’re actually studying off gassing from soft goods, household materials like carpets and clothing, stuffed animals, pillows, those soft materials that get soaked by the fire smoke during the active fire period. And then after the fire is over, they were kept inside people’s home.

And for security reasons or people just worry about outdoor air quality, oftentimes, they just kept their home sealed. So those soaked materials, they will start to offgassing, basically giving back those chemicals into the indoor space. Because the indoor space is not well-ventilated. So they just got accumulated inside people’s home.

FLORA LICHTMAN: So like, your rug or your couch absorbed all of these chemicals, and then it’s just basically offgassing them?

YIFANG ZHU: Exactly.

FLORA LICHTMAN: François, did you test your– did you sample inside your own home? And what did you find?

FRANÇOIS TISSOT: Yeah, my house was one of the first homes that we sampled, of course. We found what we find in any home in the burn area, elevated lead levels above the recommended safety limits from the EPA. We found very high levels of arsenic as well, both of which are coming from the constructions that burned around our house for different reasons. Lead was in lead paint and in lead pipes.

And the houses in Altadena were all very old. Most of them were built before the 1950s, so before any ban on lead or asbestos. And the arsenic was used as a termite treatment for until the 2000s. And so all the wood from all the houses around us was containing this arsenic, and it released it when the house is burnt.

FLORA LICHTMAN: Are people having to pay for testing for these chemicals themselves?

FRANÇOIS TISSOT: It is one of the main problems that the local community is facing. It’s that insurance companies, they have a guidebook that they follow on what to do after a fire, but their guidebook is based on wildfires. And wildfires do not release arsenic or lead or any of those toxic elements because it’s not in trees or shrubs or anything like this.

So when I asked for testing in my house– because I had already tested and I had already shown that there was lead and arsenic and all of these elements– their response was, we typically don’t do this testing, so we’re not covering for that cost. And also, there is no reason there should be lead in your house. My response was, of course, well, I have already measured that there is lead.

And they said, well, you’re not an accredited lab, so we will have to have a professional lab test your house. And when I ask that you do it, they said, well, we don’t do it in this instance. So then there was this catch-22 where it is there, I showed it’s there, but their guidebook does not say to do this testing unless there is a reason to think that there is lead, which just me saying it was not enough for them.

FLORA LICHTMAN: Right, and they don’t think that there’s lead because there’s no actual scientific res– there’s not a lot of scientific research showing where you might find lead after an urban wildfire because–

FRANÇOIS TISSOT: Exactly.

FLORA LICHTMAN: –it’s a new kind of disaster.

FRANÇOIS TISSOT: And this is something the National Academy has said. Wildfires at the urban interface need to be studied because we don’t know the risk. But it has not come to reality yet.

FLORA LICHTMAN: Yeah. I mean, there’s a wide range of contaminants, from organics to heavy metals, arsenic. There’s also benzene twirling. They all, say, have serious health effects. And insurance companies, they’re not obligated to test those chemicals at all. Because some of those, they’re not– have clear health standards published by or enforced by the government. So there are really limited testing going on in those homes during this post-fire recovery period. And we know they have health effects when people are exposed to them for a long time.

FRANÇOIS TISSOT: This is also why we started this work. Because it is very needed for the next fire. And there will be one such next fire. Because right now, one in three houses in the US is in an environment that’s called the WUI, the Wildland Urban Interface. This is where most of the expansion of the cities have happened. And those are the places where very tightly-packed houses inter-spaced with brush and other fuel can basically burn like Altadena did.

FLORA LICHTMAN: We have to take a break, but don’t go away. Because when we come back, we’re going to talk about where we go from here. Stay with us.

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FLORA LICHTMAN: OK, we’re back. Yifang, can these toxic chemicals that we’re talking about– we’re talking about asbestos and lead and benzene and others. Can they be cleaned up from a house?

YIFANG ZHU: Yeah, that’s a big question. It’s just like François mentioned. We realized that there were– how little knowledge that is out there in the scientific community, let alone guidance, on post-fire remediation. And all those uncertainties, I feel, especially for vulnerable communities, is really challenging. So there are some insights, like general guidance, I think we feel comfortable to give to homeowners and residents.

Like we know that, for example, on the air side, we know increased ventilation in your indoor space could help. Running HEPA air purifiers, and especially with charcoal filters, could help reduce volatile organic compounds, remove particles resuspended from deposit dust. Cleaning up your HVAC system is really important. Doing remediations remove those smoke-impacted soft materials from the indoor spaces– all of those could help. But we really don’t have enough data to give concrete answers about which method is the most effective or cost-effective at this point.

FLORA LICHTMAN: I mean, François, will you feel safe going back to your home?

FRANÇOIS TISSOT: That’s a very good question. Every expert that we have brought into our house, which has suffered extensive smoke damage and lead and asbestos contamination, has said, you have basically two options. You can either demolish and rebuild, and that will remove the contaminant, of course. Or you can strip down the house to the studs, and then rebuild from there.

And the rationale for them is, they do not know that they can clean the house by just cleaning the surfaces. The only way that they can envision cleaning is removing the contaminant, removing all the porous materials, including the walls and anything that was inside the walls. And that goes back to your question of, can we clean? And it’s an open question.

When the amount of contamination is low, maybe a couple times above the EPA limit, yes, cleaning is possible. You can use wet wiping techniques and HEPA vacuuming. And remediation companies know how to deal with that level of contamination. What this particular fire has brought to light is that some houses have been contaminated to such an extent that we do not know if the cleaning techniques that we have are appropriate or efficient at all. And until research is done to answer this question, then the only approach is to remove the material itself.

FLORA LICHTMAN: I mean, Yifang, how long will it take to know the health impacts from this fire?

YIFANG ZHU: Yeah, so there’s acute health effects. There’s already studies being published showing during the active fire period, the number of ER visits went up. Not only the number of ER visits went up, it’s also the abnormal blood tests from those ER visits went up relative to the previous year of the same January time frame. So the acute health effects has already been showing up and documented. The long-term health effects from those mini fires is really a big gap, knowledge gap.

FLORA LICHTMAN: Has there been any federal support for tackling some of those unknowns?

YIFANG ZHU: [SIGHS] So I have a pending [LAUGHS] NIHS grant, and that’s been pending for eight months. [LAUGHS] So it’s supposed to be a rapid grant mechanism, but clearly not so rapid. So the funding climate at the federal agency levels is definitely also not helpful in this setting.

FRANÇOIS TISSOT: Yeah, I guess I can jump in here. The climate of funding is really making it difficult to go after those kind of questions. The only reason that we’ve been fortunate enough at Caltech to do it is because Caltech was supporting this research from a few days after the fire. They immediately said, whatever you guys need to do that can benefit the community, do it, and we will find the money for it. This is what federal agencies should do. This is what those rapid proposals that Yifang was referring to should be doing. Clearly, this is not the priority right now.

FLORA LICHTMAN: François, your usual research is on, as you were saying, the solar system and how planets formed. What’s it like to go from studying something wondrous and abstract to, is my house going to poison me? Has it changed the way that you think about science or your own research?

FRANÇOIS TISSOT: It’s definitely a different exercise. There is a sense of responsibility that comes with it that I’m very aware of. And I’m immensely proud of the work that my group has been doing, trying to address such a difficult situation.

If this data had existed before, it would have made everyone’s life, myself included, so much easier. We wouldn’t have to argue for months or years on end with the insurance. Yeah, it would just have made it easier to face an already extreme challenge. If we– and by “we,” I mean my group and other researchers– can bring answers that will prevent some further suffering in future fires, then it will be worth it.

FLORA LICHTMAN: Dr. Yifang Zhu studies air quality and its health effects at UCLA. And Dr. François Tissot is a geochemist at Caltech. Thank you both for joining me today.

FRANÇOIS TISSOT: Thank you so much for having us.

YIFANG ZHU: Thank you.

FLORA LICHTMAN: This episode was produced by Rasha Aridi. And y’all, Rasha needs your help. I’m about to pivot. So that’s your warning. We are working on a show about games and gamification, and we want to hear from you. Tell us about a time when a game changed your life.

There’s lots of different ways this could go. Maybe it’s that first time you close the ring on your Apple Watch, and you turned into an exercise freak for life. Or maybe it was something more analog, like a game of Truth or Dare when you were a tween that you’ll never, ever recover from. Tell us the story about how a game changed you, for better or worse. Please leave us a voicemail, 8774-SCIFRI. That’s 8774-SCIFRI. Thanks for listening. Have a great weekend. I’m Flora Lichtman.

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