Hey, it's Flora Lichtman, and this is Science Friday. Today in 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 posed 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. Francois Tissot is a geochemist at Caltech, and Dr. Yifeng Zhu studies air quality and its health effects at UCLA. Welcome to both to Science Friday. Thank you for having me. Thank you. I want to get into the toxicology in a second, but Francois, let's start with your personal story. What happened in your neighborhood? Yes, well, our neighborhood was almost completely burned 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 unliveable and unsafe. I mean, obviously this is so personal, but you also made it professional. Why? 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 were 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 mega fires. There are new kind of threats. There is very little that is being known. There was nothing for me to make an assessment of risk from. 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. 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? What do you usually work on? 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 are usually the step one of anything we do. Except in this case, for 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. You must have felt desperate in some way to get these answers. 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. We were at the wrong place at the right time to make a difference. Yifeng, I know you have been collecting samples and testing the air for the last year. What have you found? We took three phases of measurements. We collected air samples during active fire period and then went back again and took measurements when the fire was about halfway contained. Then went out again another round to take air samples when the fire was completely put off. 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. This is especially true in homes where no one was living at the time. We know there's lots of indoor sources, cleaning products, cooking, smoking, all can produce those viruses 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. This is a really important public health message, basically saying that people really need to be aware about potential exposure at risk when they're considering returning homes. When you say inside, was it air quality? Was it your sofa was loaded with these toxic chemicals? What do you mean? 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 carbons and clothing, stuffed animals, pillows, those soft materials, they get soaked by the fire smoke during the active fire period. Then after the fire is over, they were kept inside people's homes and for security reasons or people just worry about outdoor air quality. Oftentimes they just kept their homes sealed. Those soft materials, they will start off-gassing, basically giving back those chemicals into the indoor space because the indoor space is now well ventilated. They just get accumulated inside people's homes. Your rug or your couch absorbed all of these chemicals and then is just basically off-gassing them? Exactly. Francois, did you sample inside your own home and what did you find? 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. The arsenic was used as a termite treatment until the 2000s. All the wood from all the houses around us was containing this arsenic and it released it when the house is burnt. Are people having to pay for testing for these chemicals themselves? 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. Wildfires do not release arsenic or lead or any of those toxic elements because it's not in trees or the shrub or anything like this. When I asked for testing in my house because I had already tested and I 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. 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. They said, well, you're not a credited lab, so we will have to have a professional lab test your house. When I asked if they do it, they said, well, we don't do it in this instance. 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. Right. They don't think that there's lead because there's no actual scientific research showing where you might find lead after an urban wildfire because it's a new kind of disaster. 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. Yeah, I mean, there's a wide range of contaminants from organics to heavy metals, arsenic. There's also benzene, toiling. They're all like, say, serious house effects and insurance company, they're not obligated to test those chemicals at all because some of those, you know, they're not like have clear house standards published by, were enforced by the government. So they're really limited testing going on in those homes during this post-fire recovery period. And we know they have house effects when people exposed to them for a long time. 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 Wide Land Urban Interface. This is where most of the expansion of the cities have happened. And those are the places where very tightly packed houses interspaced with brush and other fuel can basically burn like El-Tadina did. 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. When some of the scientists who helped build AI are now sounding the alarm with this kind of technology, aren't we going to build machines that we don't control and could potentially destroy us? What future is this technology rushing us toward? Listen to the last invention wherever you get your podcast. Okay, we're back. Yifeng, 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? Yeah, that's a big question. As Yixing said, like Franke mentioned, we realized that there was a whole little knowledge that is out there in the scientific community, led along guidance on post-fire remediation and all those uncertainties that feel especially for vulnerable communities is really challenging. So there are some insights, like general guidance, I think we feel comfortable to give to home owners and residents. Like we know that, for example, on the airside, we know like increased ventilation in your indoor space could help, running HIPAA air purifiers, especially with charcoal filters could help reduce volatile organic compounds, remove particles, resuspend it from deposit dust. You know, cleaning up your HVAC system is really important during remediation, 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. I mean, Francois, will you feel safe going back to your home? That's a very good question. Every expert that we have brought into our house, which has suffered extensive smoke damage and asbestos contamination has said, you have basically two options. You can either demolition 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 it's an open question. When the amount of contamination is low, maybe a couple of 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 only approach is to remove the material itself. I mean, Yifeng, how long will it take to know the health impacts from this fire? Yeah, so there's, you know, acute healthy facts. There's already studies being published showing during the active fire period, the number of ER visit went up. Not only the number of ER visit went up is also the abnormal blood test from those ER visit went up relative to the previous year of the same sort of like a generate timeframe. So the acute healthy facts is already being, you know, showing them undocumented. The long term healthy facts from those fires is really a big gap, knowledge gap. Has there been any federal support for tackling some of those unknowns? So I have an opinion and I just grasped and that's been pending for a month. So it's supposed to be a rapid, rapid ground mechanism, but clearly not so rapid. So, so the funding climate at the federal agency levels is definitely also not helpful in this setting. 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 you think was referring to should be doing. Clearly, this is not the priority right now. Francois, your usual research is on, you know, as you were saying, the solar system and how planets formed, what's it like to go from studying something, you know, wondrous and abstract to is my house going to poison me? Like, has it changed the way that you think about science or your own research? It's 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 insurance. We would it would just, 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. Dr. Yifeng Zhu studies air quality and its health effects at UCLA and Dr. Francois Tissot is a geochemist at Caltech. Thank you both for joining me today. Thank you so much for having us. Thank you. This episode was produced by Rasha Oriti 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 closed 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 a story about how a game changed you for better or worse. Please leave us a voicemail 877-4-Sci Fry. That's 877-4-Sci Fry. Thanks for listening. Have a great weekend. I'm Florian Lictman.
