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March 16, 2022

042 - Unsafe environment of post fire scenes with Gavin Horn

042 - Unsafe environment of post fire scenes with Gavin Horn

We all understand the dangers of smoke inhalation in fires. But what about the site of the fire a few days after it was put out? It looks clean, maybe even lost the smell... Is it something to worry about, or you can rush straight in, wearing your shorts and a t-shirt? Well, I guess I would not be that reckless, but if I can be honest - I don't think I would care that much about protecting myself either... At least that was me before the talk to dr Gavin Horn from UL FSRI.

Gavin spent more than a decade investigating the environment of post-fire scenes. And these places are where many of us work, almost on daily basis. Firefighters, investigators, fire researchers, constructors and demolished... And the scenes do certainly hide some threats within. In this episode you will learn a lot about them, and how these threats change as the environment evolves. More than that, Gavin is a pretty down-to-earth guy and does not imply you should dress for an investigation in a NASA space suit. You have to balance the risks related to contamination through inhalation and absorption, with risks of overheating, falling or cutting yourself, and as well with the capability to do the actual work wearing PPE. That is not the kind of discussion I get with my own H&S experts, and I appreciate this smart and holistic view a lot.

To learn more about the environment of fire scenes, you MUST read this excellent paper by Gavin Horn et. al. Airborne contamination during post-fire investigations: Hot, warm and cold scenes

You may also want to enter the gold mine of resources that Gavin has shared with me:

Transcript
Wojciech Wegrzynski:

Hello, everybody. Welcome to Fire Science Show. Session 42. Judged by the number, I guess you could expect it will contain all the answers. In the fire safety. Well, Maybe it does not have all the answers in the fire safety, but it certainly has. A lot of answers on how to be safe in fire safety. This is because I have invited the. Really nice guest dr Gavin Horn from UL. FSRI. Who's dedicated his life to research the safety of firefighters and investigators who are dealing with the scenes of fires. And we're not going to talk much about the exposure to fire or fire products as the fire goes, which I guess most of us are used to. when dealing with fire safety problems? No, we are going to discuss the scene of the fire after the fire has been. Fought off after there's no more fire. No more smoke. Just a normal looking burndown location that you need to enter. Take pictures. Investigate cleanup rebuild. A scene that looks like completely normal place, but there lies a danger in it. And, Gavin is researching that. Contamination. And it's really interesting how big the exposures are and how large the threats are. You know,, if you think about it. If you're just an occupant and you have the misfortune to find yourself in the fire. Well, that's probably once in a lifetime, even for you. But if you are. An investigator. That's your bread and butter. That's where you go for work. And if you happen to be a fire investigator, or firefighter or even a fire research laboratory. personnel. And you deal a lot of burned down buildings, building elements and fires in general. This is a very important episode to listen to because you will learn, the threats and solutions. So I'm working in the fire laboratory. I'm leading a fire laboratory. I get exposed to these things all the time. And. Already have a lot of things going through my mind in how can I protect myself better and protect my people better. In this harsh environment because, I confirm. The scene after a few days does not look very threatening and dangerous, but when Gavin put his meters in that scene, He discovered. That danger that's hidden within. Anyway, I hope I got your attention. And. this is a very important episode and I wish that all of us stay safe and I wish that, We do not have any long-term health effects. From the work that we love to do. And yeah, there's only one way to protect yourself and protect yourself in a smart way. And you will learn how to do this today. So yeah, lets spin the intro and jump into the episode. Hello everybody. I'm today here with Dr. Gavin Horn from UL. FSRI. Hello, Gavin great to have you.

Gavin Horn:

Hello. It's great to be here. Thanks for having me.

Wojciech Wegrzynski:

I'm very happy to have you. And today we're gonna discuss an important subject that touches health and life of many people in fire safety engineering. , we're going to talk about the toxic products that are produced by a fire, but in, in a very specific way, not necessarily the ones that we breathe during the fire, but what's left after a fire. And I think. Subject is really important because , I'm a very lucky to be working in my office, not really exposed to the post-fire environment, but many of our colleagues have to witness The scenes of fires, many of our colleagues have to clean after the mess, the fire does. They spent hours in the scenes and it's not once a year. It's their job. They're there every week. And I guess this can have pretty significant health consequences, right. So bring me up on the topic of bed. Where's the issue? How big is it?

Gavin Horn:

Yeah, absolutely. The question is, is well posed and unfortunately I can't give you a really great answer for, the problem, of exposures in the fire service and in particularly to fire investigators, which are a specific component of the fire service though. I might also point out that there's many investigators outside of the fire service, right? From, academics, from insurance, from rebuild, from all the different people who work in the environment after a fire has put out. We're really trying to understand what is the. What remains there and then what changes over time after the fire is gone? So we've been very fortunate over the past almost 10 years, to run a series of research projects, to try to look at what is in the air from the lens of understanding, occupational exposures, particularly carcinogenic exposures. So those occupational exposures that may increase the risk for cancer. Now a decade ago, as we began, this work, much of that was focused on the firefighter themselves. So to really put this in the right context, probably want to go all the way back to some of that work. Yeah, we want to understand what's in the air during these firefights, and there's been a great deal of research going back way before that. but oftentimes we think about the toxic exposures, particularly to occupants who might be trapped in the structure is acute risks. Thinking about the reduction of oxygen concentrations, the increase of carbon monoxide, carbon dioxide, and hydrogen cyanide among the many other gases that are produced the irritating gases and all of those others that have an acute effect in terms of, of someone's ability to, evacuate, to, make their way out of the fire them. There has been a little less understanding of some of those other compounds that may have more of a chronic concern and not necessarily to the occupants of the structure, because we want to make sure we get those out. But again, as you'd mentioned for those individuals who will be working in that environment and repeated exposure multiple times, possibly per day, multiple times per week, per month, and in over the years of an individual who works as a firefighter or a fire investigator. And so we've been wanting to learn more about what do fires produce and those fires could be in a typical residential room and contents, fire, restructured fire. It could be even up to things such as training scenarios, where firefighters are commonly in, And there's been a great deal of work that we've been fortunate to collaborate with our group at, UL Fire Safety Research Institute, along with, , others at the Illinois Fire Service Institute research program, which is actually where I spent 15 years of my career before joining FSRI at the university of Illinois and NIOSH for us. It's the national Institute for Occupational Safety and Health, who really has incredible industrial hygienists who focus on different occupations. And Dr. Kenny Fent was our, is the individual who really leads some of that work in the firefighter. And we were just trying to understand what is in the air, what is produced by these fires? What is the magnitude? Then we could start drilling down on how can we help protect firefighters using different control measures, hierarchy of controls, such as personal protective equipment, administrative controls, endurance controls, other things like that. And then moving on, uh, beyond that now to looking at some of the fire investigators.

Wojciech Wegrzynski:

And now a naive question from myself. how much do you care about what was burning? Like are the contents also important in that, or just the fact that the fire was, for example, flashover it fully developed or some ventilation, to what extent the, the flavor of the fire, changes the environment inside

Gavin Horn:

Yeah, an incredible amount. it's the fuels that are burning. Yeah. it's very important to understand what is burning whether you're dealing with a kitchen fire versus a bedroom fire, which is something we've started to look at, fairly recently, whether it involves, a living room type of furnitures, we might expect different exposures if it's in a garage, depending on what you might have in your garage, the different, chemicals and lubricants in automobiles and other things like that, whether it's an automobile fire versus a structure, fire can have an implication, training fires again, what we are using in those training scenarios. But it's not just the fuel that influences that as he mentioned, it's the ventilation. We know the more under ventilated a compartment gets, the less efficient combustion is going to be. And the more products of incomplete combustion are going to be released. Many of those are the ones that we're concerned about. So the same fuel under different ventilation configurations are likely to create very different environments with which the firefighters, and then following on the fire investigators are going to have to. So they all make a difference. Our work that we're doing, we're looking at more full-scale scenarios. There has been some work done on bench scale, and it is as with anything scaling from a bench top experiment up to a full-scale is tricky at best. I think that's the nicest way to say it, that goes for the thermal conditions, as well as the chemical exposures and chemical products. But we're looking at trying to get a handle on what is the order of magnitude, what are the compounds that are likely to be present and how much is there? And then how much can we reduce that? Getting to the firefighter by wearing personal protective equipment, right? If that PPE is effective at reducing some of those exposures and where it's not effective, what can we do to redesign that equipment?

Wojciech Wegrzynski:

So you've mentioned PPE, occupants obviously, usually don't have PPE and they will be in an environment where all of these substances may already have been released. As you said, in the introduction, we usually would care about, things with acute, effects like co or HCN, which are, we know they're toxic gases that, even in a small doses can be harmful or maybe even lethal. and now you're talking about the more complex systems that are cancerogenic. I guess these are probably some longer, , hydrocarbon chains or polycyclic hydrocarbons. So. What doses of these things are we talking about? Because if I understand correctly, it's this more complex substances that also are related to soot formation in fires. And we know that there's a lot of smoke where there is a fire, especially under ventilated one

Gavin Horn:

Yeah, absolutely. You're correct. Much of the compounds that we are interested from a occupational exposure to carcinogens are some of these longer chains, the compounds that are most commonly investigated, there's really two groups polycyclic aromatic hydrocarbons or PAH's , there's one that we see a large number of research projects focusing on. and it's a group that we have collected a lot of data in the United States, but also a great deal of work that's being conducted in Europe, in Australia in particular that are looking at some of these same types of compounds. In addition, Volatile organic compounds - VOC's in particular, we think about a specific class of those , which are BTEXS, right? So that stands for benzene, toluene, ethyl benzene, xylene, and styrene. And, and of those benzene tends to be, present in the highest concentrations. benzene also happens to be a group, one known carcinogen, uh, according to the international agency for research on cancer or , which is, uh, a group that you often will hear about when looking at individual compounds, but there's a number of other compounds that are of interest. And this is one of the things that makes it so challenging because there's individual compounds that we're concerned about. Benzene like benzo-a-pyrene, which is a type of a pH, which is a group one carcinogen. Aldehydes in particularly formaldehyde is something that we see in relatively high concentrations. oftentimes above exposure limits, occupational exposure limits, even sealing or very short term exposure limits, and is something that we see quite regularly in many different types of fires,

Wojciech Wegrzynski:

you have to bring me up in line. this type one consider again. what does that exactly mean? if you could explain it to layman.

Gavin Horn:

Well, the international agency for research on cancer, looks at different compounds as well as different occupations and. Studies the literature in the research that has been conducted. Say for benzene all of the research that has been conducted to understand the exposure risk from the research on that compound or an actually right now they're looking at firefighting, Dr. Kenny Fent is heavily involved in that work as well right now, among others from around the world, So, it's a large international group, that works on these sorts of things. And it looks at the literature and says, okay, there is enough evidence that we can say that this is a group one carcinogen, that it is a known human carcinogen. Okay. But then there's a couple of other. Categories. There's a group two a, which says, well, there's enough information here for us to determine that this is a probable human carcinogen. That would be a group two, a or two B, which is a possible human carcinogen. So those are often the compounds that we are concerned about that are either a group, one group, 2A, or group 2B doesn't mean that the others are not is just in some cases there's not enough, right? That there's not enough evidence at this point to categorize it as, as one of those categories.

Wojciech Wegrzynski:

I assume, with these, types of, toxic materials or toxic products, like when you have CO you know, what is the lethal dose? You know, what's the smallest those you can be exposed to without any effect. So you can work in those, but I assume with this there is no safe dose. Like you can be exposed to these amounts of benzene every day and you'll be fine.

Gavin Horn:

There are occupational exposure limits for benzene and for formaldehyde, they do exist. but there's also a recommendation to try to reduce exposures to these carcinogens, to the, the lowest feasible amount. So best practices to try to reduce it to the lowest feasible amount. But there are established short-term exposure limits and recommended exposure limits for compounds such as, benzene and formaldehyde. So they do exist, but we also know that it's challenging in the fire service because the exposure risk is not just to formaldehyde or just to benzene. There's going to be a mixture of these. And there's other compounds that can be released from burning materials that we may not know as well. So another part of the studies that we've conducted, and again, this work is being conducted also around. Or looking at what are some of the other compounds that get released from the structure? Not from the materials, not necessarily products of incomplete combustion, but we know there are compounds that are added to some materials to make them more stable or more flame-resistant right. Flame retardants that are added to try to reduce some of their risk from those materials. igniting once they do ignite, some of those compounds can get released into the air. And then there are concerns about the health effects from those materials, poly- and perfluoroalkyl substances substances, or PFAS are another group of compounds that are, we're becoming more aware of some of the health risks of these compounds, but we don't yet know. Do they provide a, or is there an additional risk from them during the firefight? And also during the fire investigation, after all the sudden everything has settled back down under the ground. And a fire investigator is going into shovel out the scene or to look for fire patterns or to document the damage or to do what, what has to be done for the fire investigator. Can those compounds get kicked back up into the air, which again, can be available for exposure either through inhalation or dermal exposure. So there's, great deal of different compounds that we are aware of more that we are not aware of. And others that evolve as the fuels that are inside the structures should say the furnishings or the materials that are inside the structures change. The risks are likely to evolve and to change as well. And as we have more homes that are built more air tight, and we change the ventilation configuration of these structures as the burning, we might produce other things. So it's a constantly evolving science. And this is why I think one of the great collaborations that we've been able to develop is between the fire science, fire safety engineers, our group at, at FSRI and industrial hygienists that are at NIOSH, because this is a problem that begs for interdisciplinary research. And needs that so that we can talk about how does the fire dynamics change with these different fuels and these different configurations and industrial hygienists can tell us, well, this is what we need to measure. And this is what these things means. And this is how it translates from what's in the air to really, what is the risk for the, the individual who was working in that environment?

Wojciech Wegrzynski:

Okay. so we know that there may be some levels at the widget would be expected. However, it is complicated because you're expected to an unknown mix of that after a fire. And we don't truly have a way to, I that's my understanding. We don't truly have a way to protect the, scene of a fire after a fire. we were not able to clean it because you have to investigate it and you probably want to not have damaged. And the evidence you may find, preparing it for an investigator. So. In essence, someone has to go there in this environment as it is. So, you've mentioned this environment evolves and changes over time. So it's not the same thing. Eight hours, 12 hours, 20 hours, two days, five days after the fire. Maybe you can tell me, how this scene evolves and, , how these, dangers change with this evolution

Gavin Horn:

Yeah. And again, this is something that we are a bit hot off the presses in terms of our understanding. And there's going to be a lot more presses that are necessary, , before we really truly understand this. But, in January of this year of January of 2022 We were fortunate to publish the manuscript and the Journal of Occupational Environmental Hygiene, and happy to provide you the link. So anyone can, can download that. We've paid for open access. So it's freely available to anyone who is interested in

Wojciech Wegrzynski:

I appreciate it.

Gavin Horn:

Yeah. And this is a study that actually piggybacked on one that I believe you talked about with Craig Weinschenk and Steve Kerber not long ago where we were looking at different tactics that firefighters use on a structure. And they were looking specifically at size up in a search and rescue study. So where we had fires that were, started in a kitchen and allowed to develop as they would, based on the ventilation scenarios and the water application for the firefighters, some of those stayed at. Some of those involved, the entire great room. So basically moved from that kitchen into an adjoining room they were connected to each other. What we would call an open concept floor plan. It's probably a similar concept in many other places, into those furnishings. And in another series of experiments that were done in bedrooms, again, various different sizes of fires, but the exact same fuels used in all the bedrooms and exact same fuels used in all of the kitchens. And once we were done with that, then we started looking at the fire at different timeframes when the fire investigators would show up. So the first timeframe that we looked at was, and what I'm going to refer to. So if I take a quick step back here, IAAI to international association for arson investigators, has, Manner of categorizing these different timeframes since the fire has been suppressed in terms of when these investigations might occur. And they do that in the health and safety documentation to kind of provide recommendations on protection PPE, as well as monitoring and things like that. Again, something else I'm happy to share with you. A new white paper is gonna be coming out on best practices from IAAI soon, but we wanted to look at times from each of those different categories. So the first time we're an investigator is likely to come in and start their work inside maybe during. So after the fire is suppressed, there's times where we might say, Hey, hold off on the overhaul process. We don't want you to start tearing into the walls or tearing up the scene to find any sorts of hidden fires in the walls in the back so that we can document the patterns that might be on the wall or on the ceiling or on the furnishings that are in that structure.

Wojciech Wegrzynski:

so that would be like immediately after the fire is put out, even before any action is taken to, to okay.

Gavin Horn:

Yeah. So before any action is taken to find any of the hidden fire. So the fire is put out and the investigators get there in time, in the United States, it's the truckies who do most of the work. I'm sure in many, in other countries, there's similar groups that have that same, homewrecker type of responsibility, but they go in and say stop before you do anything else go any farther. We're going to take some, we're going to take a look at this. And so that would be considered a Hot Scene A timeframe, immediately after the fire has been suppressed, potentially during overhaul or right after overhaul. So there might be some smoldering off gassing and other things along those lines that would be present while the investigator is going in. So then the next timeframe after that would be considered a Hot Scene B. Okay. And again, that's after the scene has been fully extinguished and overhauled, but it's still less than two hours. Okay. And oftentimes that's where we might do a more thorough investigation. The thermal threat has been mitigated. So the investigators will go in there may have been some overhaul done. If we're lucky we can actually even have , held the significant damage to the fire patterns. It's not always possible, but that's considered warm scene or hot scene. Up until a couple hours after suppression

Wojciech Wegrzynski:

So in the first one, immediately after the fire, you're not only exposed to the products that would be there, but also the heat, which is still in the walls. And it's being transported over the scene. And in, the second type of a scene, which would be after the building is secured and then cooled down. You may still be exposed to a little bit of thermo. it can be warm and moist probably, but it's not gonna burn you down. Right. is there any specific type of chemical compounds that form at this point, or that, are present in an arm, was a Mount in, in this point of time and later will not be seen or any specific.

Gavin Horn:

Yeah. So. When we compare the compounds that we see particularly hot scene a to the hot scene B and then , we'll move out in a bit to warm and cold scenes yo days, , for longer times. But most of what we see that are in high concentrations during those hot scene, timeframes are the same things that are in high concentrations during the firefight themselves. So the highest concentration of compounds are typically benzene naphthalene. So benzene is a VOC naphthalene. traditionally is the largest of all of the PAH is that we see. And then aldehydes often as a tell to hide is kind of the highest concentration that we see. But formaldehyde, when we compare to the relative ceiling limits, occupational ceiling limits, we often say, even though formaldehyde is a slightly lower concentration, it is. Elevated relative to some of those exposure limits. So those are the compounds, again, that we see in the highest concentrations in a hot scene, A and B, and really for the rest, much of the rest of the time. And we see that there is large drop-off in most cases, from the hot seat, a to the hot scene B. So as the fires, more thoroughly suppressed. And in, in these cases, in these fires, the windows were out of the structure. The front door was open. There was ventilation and a ventilation allows, which is again, typical with a fire of the size that we were investigating. There would be some natural Venice. and the firefighters in these cases did also do hydraulic ventilation. So that is putting a hose line in a window and putting on a wide Fogg and using that hose stream to draw air through the structure. So we see those compounds. Again, those are produced in the highest compounds during the fire that we see when we put monitors on firefighters and our other studies are the ones that we see the highest afterwards and remain, even though they tick, most of them start to decay. Aldehydes are a little different, we can talk about that, but they do begin to decay from that point. Now there is also one other, it's not a compound per se, in, in, in terms of looking at a specific vapor or gas, but particulate

Wojciech Wegrzynski:

okay.

Gavin Horn:

I in particular, can be very complex. Set of compounds, right? It's probably mostly carbon. There's all sorts of other things that may be attached to that soot particle. And the largely carbonaceous compounds there in, in our study, we didn't study exactly what was on that slip, but we were very interested in understanding the level of particulate during the firefight and in now the instrument that we used, , we did not put it in during the hot scene A because we did not want to risk thermal damage. As you had mentioned, the temperatures are elevated, not at all a concern for someone that's wearing firefighting, personal protective equipment. but for, for that tool, we did not collect that data for concerns of destroying a very expensive piece of equipment, but we do see particularly hot scene B. Very high levels of particulate during that investigation phase. And we measured over an hour. So the hot scene B timeframe was assuming you're going in for an hour, taking pictures, documenting the scene, doing all sorts of activities that you would typically do in a farce. And we were in there doing those investigation activities themselves. and we see very high levels of particulate in the air during that hour, both averaged over the entire time. but also some of the peaks that we saw not surprisingly often occurred when you were doing something to disturb. Right. So shoveling out the scene in order to try to remove anything that's dropped down from the walls ceilings of the drawers , that fell on the ground. As we're trying to document the scene, those might have to be moved, even moving furniture from one location. The other when firefighters go in and do it, has to be done during overhaul and during suppression, you know, sometimes furniture gets knocked over or move to hose, line, drag things away, people move them out of the way to get where they have to go.

Wojciech Wegrzynski:

even such a small things they, there were visible peaks in your measurements of particulate matter?

Gavin Horn:

We did not go back on a one for one peak, but the general timeframe in terms of when we were seeing these increases were often during those firefighting activities. So we didn't go back and look at a second by second basis. But yeah, so shoveling. Was one of those cases moving furniture around. And in particular, we saw some cases where dry wall actually fell a, some of our more heavily damaged structures, the ceiling and the walls were compromised. So when that comes in, then obviously that, that oftentimes when it falls, there is a lot of momentum to it, which displaces the air and then bring some of the compounds back up into the air. And we found that actually, when we start looking at some of the longer times, we intentionally started to remove some of the drywall in the cold scene. So five days after the fire part of that project was okay. Now we're going to take a look. What happens if we want to investigate the structure or the systems we wanted to keep everything kind of as tightened up as it normally would be without disturbing the walls more than I already had been. But then we started to remove some of that in the last. investigation that we conducted. And then we saw incredibly high concentrations of particulate that got into the air,

Wojciech Wegrzynski:

But here we are talking about the scene. That it's five days after a fire. You'd no longer see, firefighters roaming around in, breath apparatuis. You may be just a person who's trying to clean this place because it either has to be demolished or refurbished. and here you bring up these, concentrations almost back to what you've seen in a scene. Not far after the fire, as I understood correctly.

Gavin Horn:

Yeah. It, and this is where yo, it depends on what we're looking at. When we, when we look at what is in the air, the benzene by five days had gone down. Very low levels. Same thing with the aldehydes. We actually did see a slight increase in the aldehydes for the first day after we closed up the house. Right? So after the, after we did the hot scene B investigation for a few of them, what we did is we put some boards over the windows in the doors and we came back a day later and did the same type of investigation monitoring. And in that case, we actually saw that there was a higher concentration of formaldehyde and acid aldehyde in that environment a day later than it was after the hot scene be when we would consider that a warm scene based on the IAAI categories. And then we did that again, boarded it up and came back in three days and boarded up and came back five days after the fire was suppressed. We did see most of those other compounds start to decay away after that one day post-fire and go to relatively low levels. Even though we did have formaldehyde above short-term exposure limits one day after the firefight and above recommended exposure limits even three days after the firefight, but on five days out, when we decided to do something different, that was to pull some of the drywall off of the wall. We saw that particulate level, the average and the peak concentrations were actually higher than what we had during the initial investigation during hot scene B, because of the amount of disturbance that we created in that environment. And you brought up a great point. This could be for a fire. Yeah, it might not be the fifth day after it could be the first day. It could be immediately after the fire fight that the investigator is going to look for any sort of damage to structural components or looking at the building systems. Right. Is there any indication of damage in the electrical system? either as a cause or as a result of the fire, so, or other things like that when insurance companies come out and the other point that you made is one that, that I think needs to be reinforced more is in the building rehabilitate. Right. , when a post-fire reconstruction comes in, we want to be able to help the people who own this house to continue with their lives. So it's important for resiliency perspective of a community for an individual family, to be able to help get that home refurbished as quickly as possible. So there are groups that will come out and do that to take down any of the damaged drywall or any of this covered drywall and help start that rehab process. And this outcome is not as important, not only for the fire investigators, but for that occupation as well. And I think one thing that, that we really should help to understand, what their risks are, and we can bring this information forward.

Wojciech Wegrzynski:

Yeah. So, there is definitely need for guidance on how to safely approach this type of, buildings. And it seems that in a way, the time is irrelevant, the building has been burned. So there is until it's fully decontaminated, it probably is a source of threat. No matter if you go there immediately or even five days after. so what's the response we have, I guess that's the personal protective equipment. That's the, that's probably the only thing between you and the cancer organic compounds in there. But I assume that's this beyond just breathing approach. in my lab, I would focus in, on, on protection of, my breathing, system. But, these things get on your clothes, get you on your again, get on your skin. You have already mentioned that in the podcast. So like how protected we should go in there.

Gavin Horn:

Yeah, boy, we can spend a whole hour talking about this. it's, it's a great question. And again, another place where we're getting more knowledge, as we move forward. So, I will try to answer this in a way that makes sense, but there's a couple of different ways. I want to take a look at that. First of all, is understanding the routes of exposure. And then I want to come back to talk a little bit about some of the trade-offs in, in the personal protective equipment, because you've rightly identified where we're at is the most common ways of protecting, the fire investigators. But when we think about how these contaminants. can get into the human body. I th there's there's routes that any contaminant, anything can become absorbed or can get into the human body and then become a dose. Right? So the most common routes are inhalation absorption. Typically we're thinking about absorption through the skin ingestion. There is also injection, right? But typically that's not something we're too concerned about at this point. Now you could step on a nail that's covered in certain it could get in there. There are ways that, that you can get injection, but we typically focus on inhalation, absorption, and ingestion, and think about ways to protect firefighters from each of those. Immediately. We often go right to the inhalation, which is right, because that can get into your lungs. And there's a massive amount of absorption that can occur in the lungs. And there's a host of different risks that come from some of those compounds getting into the law, into the airway and into the lungs. In addition to the risks for cancer.

Wojciech Wegrzynski:

we didn't touch it. What was the size of this particulate matter? What was it like?

Gavin Horn:

Yeah. So we looked at a bunch of different cut points. So we looked at the total particulate and then at 10, at 2.5 micron in N sub one micron. So we didn't, we just looked at those as cut points. We didn't look at anything smaller than that, but these are small enough. Once you get down to that sub micron, obviously we're very concerned about where particular of that size can start to, to end

Wojciech Wegrzynski:

so we're talking about particulars that in assumption can penetrate your lungs and, get into your bloodstream and then go. Okay. So let's, let's go back to the protecting guys. Them.

Gavin Horn:

Yup. Yup. Yeah, the smaller, the particulate, the deeper, it is likely to be able to penetrate. So we want to be able to protect the airway of the firefight. the larger particulate may deposit higher than the airway, low, smaller particulate, deeper down there's concerns for carcinogens resulting in cancer, eventually in the fire service. But there's also some other respiratory concerns that we have with the exposure to these particulate in these compounds, you can also breathe in some of the vapors, the benzene in the formaldehyde, and Acklin in addition to carbon monoxide and hydrogen cyanide that are likely still present in the environment and their acute effects. So the number one thing we often think about is respiratory protection and the best thing that exists on the market at this point is a self-contained breathing apparatus. It has the highest level of protection that we can provide against any compound, Because we're bringing our own air with us. This is where we need to start thinking about trade-offs as well. And what are the limitations of an SCBA? And you might have investigations that are taking multiple hours and firefighters who are fire investigators who need to shovel out doing some, some significant work, right? There can be a fair bit of work moving around things in the scene and doing some of that shoveling, wearing protective equipment. And so the SCBA, adds weight. It adds a restriction to movement. So we need to balance the benefit of reducing exposures with the risk of increasing the heat stress. The resistance to movement, which can change biomechanics slips, trips, and falls are one of the leading cause of injuries. Heat stress is an important injury, particularly for those who might have cardiovascular concerns. So there's also operational challenges when you're wearing an air bottle that is rated for 30 or 45 or 60 minutes. And of course, that's assuming you're breathing at 40 liters per minute, which works pretty well for us. Just kind of sitting around or walking around. But once you start doing heavy work, you start getting through that air a little more rapidly. It's also not always that easy to make diagrams and to take pictures and all these other things. So part of what we're trying to do by identifying what is in a year and what is the magnitude and the concentrations is understanding, are there other respiratory protection that can be used that relieves some of that heat, stress and restriction, but provides. protection things such as air purifying, respirator, or a powered air, purifying respirator, a Papper. And even once you get farther out, can you move to a full face respirator that has specific cartridges that can be used? So these recommendations are still evolving and again, in this IAAI white paper, that will be coming out this year, there are specific recommendations that will be included based on these different timeframes. Fortunately, during most of these timeframes, we don't see a lack of oxygen, right? So we're, we've, we've returned to an environment that has a relatively high oxygen concentration, which could allow for some of these that do not require necessarily supplied air, but that also needs to be taken with a grain of salt, because there are places where you might be able to get to where that's not the. But later on, as we move into the warm scenes and cold scenes, can we switch out to a full face respirator that has the appropriate cartridges in it? And based on the study, some of those recommendations have changed. we know the particulate is one of our biggest concerns, right? So we have to be able to protect from the particulate. And that's where those Kartra dress Raiders work quite well. Right? You can get an N 95 or even better a P 100 or something along those lines, but some of them also have different cartridges that can help to reduce the risk from some organic compounds. And there are some that specifically are labeled for reducing risk for formaldehyde. And that's actually a change now that, IAAI has made is to include protection from formaldehyde. during these fire investigations as well. So these are some things that we discuss in a manuscript in terms of how to protect the inhalation risks. but we also need to understand that there's a trade off between inhalation risks and the other things that have to be done on the fire ground and the risks for other injuries, such as heat stress, such as slips, trips, and falls.

Wojciech Wegrzynski:

That's interesting. You you're looking on the holistic picture because it makes a lot of sense because it's like you cannot overprotect , the person to the point where they are unable to do their job, then essentially they will have to spend more time doing their job. They will have to, as you mentioned, uh, be exposed to more heat stress, or more fatigue, even, lower, their productivity. And, if in the end, you're interested in specific, substances that are in the air. Like you mentioned, particularly in, in particular,

Gavin Horn:

Yeah.

Wojciech Wegrzynski:

it is interesting to, to find like dedicated solutions to protect against this true. And, help you do your job quicker because I guess the ultimate protection is not being at the scene. So the sooner you're out, the better it is for you. Right. And, that's cool, but that's respiratory. now let's talk about the ones that you can absorb through your skin.

Gavin Horn:

Okay. Yeah. So skin, absolutely. One of the next things that we're, we're really starting to understand, particularly in the fire service for the response, those on the suppression side, wearing SCBA, we still see exposures, particularly to benzene, so we can see benzene that's in the air and it benzene, it gets into the firefighters body and is, excreted through the urine metabolites of, benzene which is your through the urine. Or we can see in the breath afterwards. So we know that even wearing an SCBA, the firefighters can be exposed to benzene and that next, most likely route is absorption through the skin. skin happens to be a very large organ of the body, right. And there's a whole lot of surface area. There is also a lot of research right now, trying to understand which compounds can be absorbed through the skin. How quickly can they be absorbed through the skin? What influences that like skin temperature and other things along those lines, they all likely have some impact in terms of how compounds such as benzene or others can be absorbed through the skin. But we do know that it's important. So we also want to select protection for the skin in a same manner. As you mentioned, the holistic perspective as we would, the respiratory protection it's for thinking about a Hot Scene A or B scenario, we know there could be a thermal threat there as well. Right? So something like the fire service turnout gear that has that thermal protection as well as provides a barrier. It's not a perfect. But it provides a barrier for some of those other compounds to get onto the skin might be appropriate. Once we get later on where the thermal threat starts to go away or has gone then might be appropriate to transition to something like a Tyvek suit or something like coveralls or something along those lines that covers as much of the skin as possible, but may not provide the same thermal burden, right? The PPE not only protects from the environmental heat, but also doesn't allow the body to the sweat, to evaporate, which is how we cool down. So again, we've got that trade-off between protection from the chemicals versus risk for increasing heat stress, and the more difficult movements that you might have in there. So that selection is something that. The fire investigator needs to make again, at a holistic perspective, what are the main risks that I'm facing? Is it the heat? Is it the chemicals are in the air? Is it the likelihood of tripping and falling? Is it the risk of abrasions or getting cut when operating if there's a lot of glass or other things on the scene, right? There's other things that we need to take into account when we decide what protection to use. And that last point is one thing that I really want to highlight, in that gloves is one of the pieces that we have recently found out, particularly for firefighters happened to be one of the most contaminated pieces of personal protective equipment that we have. And one that we largely ignored. So we often start at least when we started our studies. 10 plus years ago in many other studies are done around the world. We really look at what is the contamination that gets on the bunker gear, right? And then how can we clean the bunker gear or how does that come home with us and cross-contaminate things. But we also started taking samples from the gloves that firefighters wore. And, in hindsight, it should not have been that surprising because when you think about what firefighters do with their gloves as you're crawling through the scene, as you're moving things around that are covered in soot, they may be water on the ground. So it gets soaked into the gloves. So we take care when we pick up glass, because we're concerned about the cuts that can occur there, which is the right thing to do as investigator. But also those other things that we pick up the can, cross-contaminate the gloves. And then now we're taking those out with us and gloves Are notoriously difficult to decontaminate, particularly firefighting gloves. so there's a real challenge in getting those clean. And furthermore, one of the first things that comes off, once you come out of a scene, whether you're a firefighter or a fire investigator is oftentimes those gloves, because you can immediately cool down. It helps you to take off helmet, your respiratory protection, everything else that is. And so instead of taking the gloves off with care, we often take those off, like you do skiing gloves, right? And you're holding them now, thus incredible on a contamination. That's on the outside of the gloves. It's protected us somewhat. And now we take those off and we're holding them and all that contamination goes back on the inside of our hands. And then as you take off everything else in your respiratory protection and you wipe the sweat out of your eyes, and maybe you've got a little bit of snot running down your nose, if it's one of those days, right. And all those different things. Transmitting that contamination from your hands to all these other places where it can go into the body. So cross-contamination from gloves is one of those things that we need to be much more aware of. And, we need to teach firefighters and fire investigators. It's important to take the gear off with the same kind of care that you put it on and it, you wear it in the firefight in United States. We make that analogy with, EMS providers, emergency service providers. you would not go on an EMS call without. Latex gloves on, or some form of gloves to provide a barrier for body substance isolation. And we are trained from the very beginning to take them off in a very specific way so that the outside never comes in contact with your hands. So we can take anything that might be potentially infectious or potentially contaminating. And it goes in the garbage, we are trying to have that same impact on how we take off gloves in the fire service and in the fire investigation community. So that if that gear does protect us, like it's designed to which we hope it will. We don't defeat that protection as we take the gear off.

Wojciech Wegrzynski:

And when they, with the ingestion, I guess you just don't eat things you find on the fire scene and you're breathing pretty safe.

Gavin Horn:

You would think that that's part of it, but the other part is you get now you've got dirty hands. I mentioned, wiping your skin everywhere else, but it's common the U S fire service now to go to rehab after you've done the fire. So rehabilitation, you go and you get checked out, try to get a bit of water and eat some food. Quite often, that food is finger food. And if you don't wash your hands before you start eating that food with your hands, now that's coming in with the food. So then you're ingesting and the other route is an respiratory protection can take care of this. If you don't have your airway protected, you can get some of those materials that land in the mouth or the upper airway and can be swallowed that way as well. So protecting the airway there can also help reduce some of the ingestion, but yes, it's a good idea not to eat things on the fire ground, I think is a, is a general thumbnail.

Wojciech Wegrzynski:

even I figured that, uh, I really appreciate that, you're working on procedures and, I think if this, safe ways of, removing , your safety gear can become, some sort of a habit. And it's obvious to you that you do that, then you do that every single time. You can truly fully benefit from the effort you've put in working in this protective equipment, because we all know it's in a way harder, annoying, It's more difficult to work in protective equipment and anyone who ever done that, it knows that, it would be great to, to not wear anything, but that is not really smart. And I think, considerations broth in this talk, go well beyond just the weld of investigators and firefighters for us fire laboratories. We probably go through similar exposures. And even though we work in, , well ventilated, spaces we'll and anyone who's seen a fire lab that is not new, they know , the colors will be black and gray and then dark, which does not come from the pain that's all the stuff that we've admitted over the years. So I guess many, many of the advices in here are as relevant to the, fire laboratory personnel.

Gavin Horn:

No. Yeah, that's right. And something that , we're learning as well in terms of our fire research to implement some of these practices in to improve these practices along the lines that you're talking about in the laboratory, in the field, we want to be able to protect our people as well. One other thing that has become commonplace or starting to become complacent, the fireground that might also work in the laboratory to reduce that dermal exposure is skin cleansing wipes or, washing more regularly, out in the field. you might not have access to showers or other opportunities to very quickly do a thorough wash, but we know the absorption through the skin occurs over time. So it's not only what gets onto the skin and the magnitude of what gets out of the skin, but the amount of time it's available there to be absorbed. So, having wipes out there so firefighters can clean their hands off as quickly as. So investigators can be doing that before they go back to the station. Then also once you get back to the station to get a more thorough shower in cleaning as quickly as possible to get as much off of the skin as possible and reduce the time that is available to be absorbed through their skin. So another piece that can be done with, our investigators and with scientists is if you're out in net smoke environment, prioritize getting that skin cleaned as quickly as is feasible. it might not be feasible to do immediately, but the less time it's there, the less time it might be there to be absorbed. So another thing that might be able to translate across these different disciplines,

Wojciech Wegrzynski:

The

Gavin Horn:

hour passed

Wojciech Wegrzynski:

so quickly, I had the list of questions on heat exposure and, the things related to thermal stresses. So I already would like to book a parts to sir, when that is needed, for sure. But, I really appreciate this, talk. it's an important subject and it's touching so many people, I think more and more of people know and understand this stress. And that is a good thing, but there's still a big jump from understanding to. Protecting, and they really appreciate the efforts to protect in a most, reasonable way that allows you to perform your job the best That's very nice to know that actually effort isn't going in this direction because it makes a lot of sense. maybe for the end, you would like to shout out some resources I'm going to pop them , in the show notes as well. Maybe the cancer awareness or the UL programs for research. I, you guys provide so much great resources and I've already said that like a hundred times in the episode with Steven Craig, but I'm still amazed with the amount of knowledge you share with, with the community. Thank you so much for that.

Gavin Horn:

Yeah, well, well, thank you. in thank you for the opportunity to share this with the community that we may not always be able to, to reach as easily. much of our dissemination does focus on north America. but this is an issue as you rightly point out that is important everywhere, everywhere. There's firefighters, everywhere. There's fire investigations in everywhere. There's fire research. These are issues that are important to consider and to figure out how to address. And I would say we've come a really long way in the last decade. You know, we think about where we were at in the U S fire service and us research 10 years ago. And we're just scratching the surface, but it is something where we know a whole lot more and a lot more changes are being made than we might expect. And there is, as I've mentioned a few times before a great deal of research, that's being conducted in Europe, in Australia and other places around the world. But some of the resources that we make, freely available can be found on our web. At fsri.org. if you go to the website, you can search, different topics. if you're interested in investigation, you can click on a button or actually check a box. And then all of the work that we do on fire investigations is right there, including the study that we have ongoing in that paper I mentioned, and I'll send you the direct link to that paperwork. People can download it directly from Journal of Occupational Environmental Hygiene, but you can also look at broader health topics. So if you click on that box, all of the work that we have done that looks at the health-related concerns during fire suppression or residential structure, if you want to go back to learn more about that source term, right? Not just the source term for the temperature changes and for the heat that's released, but the source term, what is in the air during the firefight or during training scenarios. All the way up to the investigators, which is where we're at right now. All of that can be found right there. There's also one other resource, at the Illinois Fire Service Institute, a research program, I FSI research. There's a cardiovascular and chemical exposure, risk toolkit, which is again, something I'll, happily send you that link where all of the studies that were sponsored by the department of Homeland Security, , all of the papers, if you're interested in the academic peer reviewed journal articles, there's about 20 articles that you can find right there that provide the science behind some of the recommendations. And then there's some translation tools for those who might be in the fire service, who are interested in, what might this mean for me in terms of policies or in terms of how other people are thinking about these problems or implementing these problems? And then there's teaching tools, which really points back mostly to some of the online programs that FSRI has conducted, which you can find directly at the fire safety. On our website as well, where we take that information. And in much like what you talked about with Steve and Craig earlier translates that. So the firefighters can understand that in an hour long course, where they can learn that material, learn what it means and often can get tested and get credit for that. If that's what they would like. So all of those resources exist. The last one I'd give a shout out to at this point is NIOSH the National institute for Occupational Safety and Health, , Kenny Fent and his team are leading the efforts here in the United States, Logan there's multiple other projects that are ongoing in the us and Arizona and Florida in Illinois and in New York. But NIOSH has a great deal of information. And Kenny is also leading the NFR or the National Firefighter Registry. So developing a registry for firefighters so that we can really get a good handle on the number of cases and incidents of cancer in the fire service and how that relates to the general population. That's been done around the world and in many different places, but this is going to be one of the largest, not the largest one in the U S so all of those are great resources for people to get a handle on some of the work that we're doing. Compare it to the work that's going on in your neck of the world and hopefully collaborate and build off of each other. if any of your listeners have any questions, my email address, happy to make that available. It's just gavin.Horn@ul.org. It's pretty straight forward. Happy to answer any questions about what we have done, what we're doing right now. There's more work that's coming and hopefully how others can, can build off what we've done or can collaborate to help make firefighting and fire investigating and fire research, safer occupation.

Wojciech Wegrzynski:

That's good that's a vault... good that there is no dragon, , safeguarding, this vault of gold that you have just provided. It is just there it's much easier , than, , getting a treasure. so thank you so much , for making this available and I'll do my best to put all of this in show notes. So the listeners have easy access to them and, yeah. Gavin, thank you so much for joining me in the, in this podcast and, see you soon, man. That's inevitable.

Gavin Horn:

Absolutely looking forward to it. And thanks again, really appreciate it. and best of luck and stay safe.

Wojciech Wegrzynski:

Cheers, man. And that's it. Thank you for listening. As promised it was full. Of advice of what's going on in. hot scene and a cold scene and full of advice on how to deal with the dangers in the best way. Some of them that can be readily implemented. Like I'm taking care of your gloves and protecting your. airways and choosing your personal protective equipment. In a way that the lines with the threats on the field. So. Plenty of good advice. And so, so much more in the resources that Gavin has. Sends me. So make sure to check it out. And please stay safe. Whatever you're doing in the fire safety, please stay safe. And if you like. Learning more about how to stay safe and, How to know fires, you know, there's a Fire Science Show episode every Wednesday. So see you there next Wednesday by.