E15: Wildfire Research, Part Two | Nan (Nancy) Ma, Assistant Professor, and Rachel Hurley, PhD Candidate, Civil, Environmental, and Architectural Engineering

Jon Cain:

What comes to mind when you think of the damage wildfires can do?

Do you picture a blackened landscape of toppled trees and torched soil?

How about the smoky remains of a burned-out building?

Today on The WPI Podcast - we’re exploring another impact of wildfires – poor air quality, *even* indoors.

Researchers at Worcester Polytechnic Institute are studying this impact so that homeowners, building designers, and communities can understand the risk.

The goal is to inform and minimize people’s exposure to wildfire smoke particles and harmful substances.

Hi. I’m Jon Cain from the marketing communications division at WPI. This episode brings you news and expertise from our classrooms and labs. I’m here at the WPI Global Lab in the Innovation Studio on campus. This is the second of two episodes exploring wildfire research at WPI. Today, we’re talking about research on wildfire smoke from our Civil, Environmental & Architectural Engineering Department. My first guest on this episode studies exposure to wildfire smoke particles indoors – particularly in sleeping environments and how that exposure affects the quality of sleep children are getting.

Nan “Nancy” Ma is an assistant professor in the Department of Civil, Environmental & Architectural Engineering at WPI.

Nancy, it’s great to have you on the podcast.

Nancy Ma: Thanks, Jon, for having me to talk about this important topic. 

Cain: It's a pleasure. So, you and your lab study a lot of aspects of the environment inside buildings, the places where we live, sleep, and work. What motivates you to do, uh, this research? 

Ma: Yeah. Um, you know, we both are interested in studying built environments because they're like living machines that affect how we feel, you know, how much energy we use and even how healthy we are. And, you know, also people just do not realize it, but we do spend about 90% of our lives indoors.

So, things like air quality, temperature, and light that from outdoor is not as important as they are in built environment that really matters, right? Because we spend 90 times of our life indoors rather than outdoor environment. So, my team and I, we just wanted to make sure buildings help people stay comfortable and healthy, and whether it's keeping them cool during a heat wave or filtering smoke during a wildfire or lighting and just the right amount of light for learning or working. We also try to help buildings just try to use energy wisely so we can reduce pollution and protect our planet. 

Cain: There's a lot of different factors that go into indoor air quality. Um, but today we wanted to really focus in on the wildfire impacts and, and one of the studies that you've done was about how wildfire smoke, uh, inside a home can impact children's sleep health. Why did you decide to study this in particular? 

Ma: Yeah. We decided to study this because, you know, indoor air quality has a direct and a measurable impact on how well people sleep. Most of the existing research has looked at adults during the day, no matter that they are awake or working or exercising, not at children while they're sleeping. Sleep is a unique time because we cannot adjust our environment while we're asleep and children are especially vulnerable since their lungs and brains are still developing and poor sleep can affect their health, behavior, and learning. With more wildfires happening and people staying indoors to avoid smoke, we wanted to understand whether the air quality inside of their home is healthy enough for them to sleep, or how much of efforts we have to put around the corner to help improve it, to support healthy sleep.

Cain: I think it's a really good point you make about when you're sleeping, there's really nothing you can do. You don't really understand what's happening around you as opposed to maybe when you're awake you can, you know, try to get indoors and you might be more cognizant of if you smell smoke. Um, I'm wondering if you could talk a little bit about the sleep disruption that you mentioned. So how exactly does smoke exposure, um, disrupt sleep? And how does that tie to the overall health and development, of children in particular? 

Ma: Mm-hmm. Yeah, of course. So, you know, when there is smoke in the air, tiny particles, we usually scientifically call it as PM 2.5, um, can get into our bodies and make it harder to breathe while we sleep. And I wanted to talk about what is  PM 2.5 in case you don't know, um, the PM stands for the particulate matter and the 2.5 right is next to the PM is basically a reference to those articles being no more, no more than 2.5 micrometers in diameter. So that means it is pretty much about one 10th or one 20th smaller compared to your hair that that's very tiny, tiny particles that we're talking about here and those particles, right, can cause swelling inside of our airways, which sometimes leads to a problem cause sleep apnea, um, that means the airway closes off again and again during the night, so the person stops breathing for a few seconds at a at a time. This makes it hard for a body to get enough oxygen. And when that happens, kids can feel tired during the day and have trouble paying attention in school or even have a higher chance of health problems like high blood pressure later on.

Cain: So sleep apnea obviously can be a, a significant issue for any time, but I imagine there's some particular, risks associated with, sleep apnea in children. 

Ma: Yes, that's absolutely true because, you know, it's very hard for kids to be realizing that they experience the sleep apnea. For children it's gonna be more risky than the adults because they just cannot be aware of that type of situation 'cause for adults, like they can be aware and they can try to avoid, adjust their sleep position 'cause you feel like it's stuffy around your lungs. But it's very hard for for kids to be aware of that. And if they don't let their parents know, right, their parents wouldn't be aware of that. So I think in that case it's gonna be more risky 'cause they have less awareness. Of the sleep apnea than adults.

Cain: Nancy, one of the things I thought was really interesting about your study, uh, it points out that air quality can vary a lot, uh, depending on where the sample is taken from. Um, can you explain that to us? 

Ma: Oh yeah, of course. You know, just one, key finding from our recent study is that ambient, right? The outdoor environment and the indoor environment is any environment inside of the building and the personal exposures, right? Our individual level or our, um, air quality around our breathing zone to wildfire can really be different from each other. Um, the ambient quality data often taken from outdoor monitoring stations doesn't always reflect what individuals are actually breathing inside of their homes because, you know, we always have the buildings as the mediators or setting up the physical boundary between indoor and outdoor. And also buildings vary in how well they keep smoke out based on factors like ventilation, filtration, and even the time of day when windows are opened. And all those factors can significantly different and differentiate, you know, the air quality that we're talking about at different scales and levels and personal exposures can particularly differ because that further depends on a child's sleeping position, which changes the breathing zone definition. So for example, a side sleeper might not get the full benefit of the air filter across the room they have, uh, their back to. So relying completely on outdoor measurements or even a measurement, taken in a different part of the room or the part of the, bedroom can underestimate or misrepresent the actual exposure and health threat. That's why it's critical to measure exposure at multiple levels, to understand its real impact on steep health. 

Cain: Well, with that in mind , your study looked at the air quality right next to the person sleeping. How did you obtain that, level of air quality data in that particular environment?

Ma: Yeah. So the first thing that I have to admit is, you know, this type of research is highly cross-disciplinary. I am an architect and building scientist by training. My expertise is really in, um, the built environment. So we had to partner with researchers from the Children's Hospital of Philadelphia, CHOP, and Dr. Ignacio Tapia from the University of Miami Miller School of Medicine, uh, who is an expert in pediatric sleep medicine and pulmonology. So together we recruited children as study participants and conducted extensive monitoring of their sleep environments and everything from environment, uh, quality or air quality to temperature, to noises, as well as their sleep patterns. So we also collected self-reflect, uh, self-reported sleep quality to capture their perceived experiences. And it has been really a multiple year effort that brings together building science and clinical insight to better understand how bedding environments impact children's sleep health. 

Cain: Well, I'd love to talk a little bit more about what you learned and in particular, when it comes to assessing air quality and sleeping environments. When the wildfire smoke is present, based on what you learned, how should a family think about laying out the space where their kids are sleeping? 

Ma: Based on our findings, you know, I feel like families should prioritize creating a well-sealed, well filtered space for children to sleep when wildfire smoke is, uh, present. Start by choosing a room that can be easily closed off from the outdoors when with tightly sealed windows and doors, and try to use a portable air purifier with a HEPA filter if you can have that option or something available at home, ideally rated at least MERV 14 and place it as close as possible to the child's breathing zone and try to run it continuously during the wildfire events or during the smoke events. If your home has a central, uh, HVAC system, like most of the U.S. homes, like with the filtration system, it could be better to sleep in a room with a wall vent if you're a side sleeper rather than having a vent on the, on the ceiling. So the goal here is try to have multiple opportunities or create   a clean breathing zone, uh, in the bedding environment or in the bedroom where children can sleep with minimum exposure to wildfire smoke. 

Cain: It's really interesting that the smoke can get in through a number of different ways, the gaps in homes, the gaps in doors and windows, and that, you know, air filtration systems, depending on their quality, may be able to filter out more or less of that.

You mentioned vents that are part of HVAC systems and how close a sleeper might be to them, but there's actually two different types of vents in some of these systems. Uh, what should people know about that and what did your study find as it relates to, those locations?

Ma: Yeah. So, um, basically the other important findings we found in our paper is the HVAC layout. That means where you actually have your supply air vent and your return air vents matter a lot as well. So that's usually, we call it scientifically in the way we call it as HVAC layout. So, um. You want to make sure your breathing zone is as close to your supply air vent as close as possible. So that means the fresh air can directly clean out your breathing zone and your return air will help to download all this polluted air and pump it back to the outdoors. So, um, if you're not a hundred percent sure where to find your supply air vents, you can just feel if you have bunch of air flow coming from the vents, that's usually we call it as supply air vents. The return air vents that you basically cannot feel any air pressure, but both of the vents altogether will create the air circulation in your bedroom. So we wanted to make sure that your bed will be positioned next or close to the supply air vents where you can have the fresh air directly circulating around your breathing zone during the wildfire smoke. We found that most, in most cases, the supply air vents were basically your HVAC system and trying to take the outdoor air in and with some kind of filters you're having with your HVAC system will be helping to clean out a lots of smoke inside of the air. If you're thinking about where would be the best place to have your bed then it's better to figure out where would be the supply air vents 'cause that means the air will be going through all kinds of the, uh, the filtration system or the purification system as part of your HVAC system.  If you have MERV 14 or HEPA filter as part of your HVAC system. So the air directly coming from the supply air vent will be the cleaner one. So that's basically, a strategy, if you wanted to use the same amount of energy, right, you know we’re not talking about you have additional air purifier, that will be super helpful to think about how to take advantage of existing HVAC system with some kind of MERV filter or HEPA filter you have at your home. 

Cain: Great. So how do you hope engineers and building designers, for example, can use your research in this area? 

Ma: Yeah. So I think that's a very good question for me, and that's something I always wanted to do, uh, as a researcher, uh, in my career. So I think like one takeaway from our study is that outdoor air quality data, while it's very important, but doesn't necessarily reflect what children are actually breathing in, uh, in their bedrooms. So the air near the bed often called the breathing zone can be very different due to building characteristics, ventilation system, as I mentioned earlier, um, we need greater public awareness around this issue, particularly about the effectiveness of high efficiency filters. Those with a MERV rating of 14 or higher which can significantly reduce harmful wildfire smoke indoors. 'cause you know, if we have higher MERV rating, usually it's gonna cost a bit more. But, you know, I think to me it's worth just spending a bit more money to help reduce the harmful wildfire smoke, especially during, uh, the, the smoke period of time. Um, and I think like beyond the individual action, uh, we also hope that our findings can inform building codes and public health, uh, guidelines. So just for example, code developers could consider requiring more effective air filtration systems in homes schools and, and childcare settings, especially in regions prone to wildfires to better, to really better protect vulnerable  populations like, like children.

Cain: Nancy, this has been really interesting, and I think it's given a lot of folks, um, some helpful information to think about when they're thinking about the quality of air inside their homes, especially if wildfire smoke, happens to be present. Um, thank you so much for talking with me about your work.

Ma: Yeah. Thank you so much, Jon, for, for having me, and I hope some of the tips I offer in my interview can really help some of the people to reduce their concerns or provide some, actual strategies to, you know, mitigate, what kind of actions they can take, uh, during wildfire smoke. And thanks for having me again.

Cain: You're welcome. It's great to have you. Nan Nancy Ma is an assistant professor in the Department of Civil, Environmental and Architectural Engineering at WPI. My next guest also conducts research on the impact of wildfire smoke when it gets inside a building. Rachel Hurley is a doctoral student in WPI’s Department of Civil, Environmental, and Architectural Engineering. Rachel, thanks for joining me.

Rachel Hurley: Hi, Jon. I'm happy to be here. Thanks. 

Cain: So you're studying a topic that I hadn't really thought about before. Um, how wildfire smoke is adsorbed by different materials inside a building, and what happens next when that smoke gets absorbed. Uh, tell me what inspired you to look at those questions.

Hurley: So, what we're seeing is that there have been more catastrophic wildfire events as well as more people living in wildfire prone areas along the wildland urban interface, which is where human settlements and structures are in contact with forested areas that are prone to wildfire events. So, what we're seeing is in these catastrophic wildfires along the wildland urban interface. For instance, in January during the L.A. Fires or in 2021 during the Marshall Fire in Colorado. What we're seeing is that in people's homes that have survived, when people return home they find that their homes are almost unlivable because of this intense smell of a camp or even chemical fire. And so this is a large concern for human health because what we think is happening is that the indoor environment has this large abundance of indoor surface reservoirs. So, these are indoor materials such as furniture, walls, floors, and because there are so many materials and material surfaces that when wildfire smoke infiltrates indoors, what we think is happening is that the volatile organic compounds present in wildfire smoke, and these are the gaseous pollutants in wildfire smoke, are actually sticking and absorbing inside the materials. And this is kind of similar to a sponge soaking up water. So these materials are soaking up the volatile organic compounds. And so when people describe their homes as smelling like a campfire or a chemical fire inside for weeks to months to even up to a year after the wildfire event, this is because of the VOCs trapped inside. The materials become sources for VOCs, and this re-emission is occurring for this period of time prolonging the exposure to wildfire pollutants. And VOCs aren't only present in wildfire smoke. They are formed from processes like combustion when, um, materials or vegetation burns. But VOCs are inherently present in many building materials, so they're already in the indoor environment. It's just the added source from the wildfire smoke as well.

Cain: That's really fascinating. I hadn't really thought about how wildfire smoke can have a long lingering impact and be variable and, um, really I hadn't thought about the impact inside of a home. Uh, you mentioned volatile organic compounds. Um, I'm wondering if you could talk a little bit more about what they are and how they affect people when they're exposed to them.

Hurley: Yeah, definitely. So volatile organic compounds are pollutants that contain carbon, and they're commonly emitted from solids and liquids into gases that people can inhale when they're in the nearby air. And, um, volatile organic compounds pose many threats to human health. Um, and these range from short term impacts such as eye, throat, nose, irritation, and coughing, all the way to some volatile organic compounds such as benzene or formaldehyde can be carcinogenic to humans and our exposure to volatile organic compounds sourced from wildfire smoke really depends as well on the dose. So, what we're worried about with indoor VOC exposure is even though the concentrations may be much lower than they are during a wildfire event, if people are exposed to these VOCs for weeks to months to up to a year after a wildfire event, then their overall dose would become much larger and this could potentially be a concern for human health. Although exposure to VOCs is unhealthy for all individuals, the level of concern for exposure to these volatile organic compounds may be different depending on the individual. For some, someone who may be very healthy, it might not be as much of a concern, but for more vulnerable populations. Such as those with asthma or especially pregnant women, exposure to VOCs can have more severe health outcomes. So although exposure to wildfire-source VOCs may not be at the forefront of everyone's mind, it's important to work towards creating these clean air spaces and reducing exposure for everyone, but especially those who are more vulnerable.

Cain: , The exposure to these compounds is, uh, clearly a, a serious issue. So I'm hoping you could tell me a little bit more about how you conduct the research that you do on this topic.

Hurley: Yeah, so my work specifically focuses on characterizing the re-emission of the volatile organic compounds or VOCs from different indoor building materials. And my work currently, I'm advised by Professor Shichao Liu, um, but we also work with Fire Protection Engineering and more specifically Albert Simeoni. And in this past fall, I had an internship through the NSF GeoHealth internship with Aerodyne Research Inc. Where I was mentored by Dr. Chenyang Bi. During the study, we focused on firstly, how the different building materials themselves may influence this re-emission of volatile organic compounds after being exposed to wildfire smoke, and also looking at more of the properties of the volatile organic compounds themselves. Um, for instance, their volatility, which is characterized by their vapor pressure or their affinity for different types of surfaces, whether it's organic or water based, which is if the VOC is more hydrophobic, water repellent, or hydrophilic, water loving. So, the volatility of a compound is pretty much the tendency to vaporize into the gas phase from a solid or liquid and organic compounds can be described as being volatile organic compounds or semi volatile organic compounds. SVOCs are much more likely to be found inside materials in the solid phase, while the volatile organic compounds are more likely present in the air. And that's what's really interesting about indoor air quality is that the volatile organic compounds, which are predominantly present in the air outdoors, because there are all these indoor surfaces, can actually adsorb and behave traditionally like semi volatile organic compounds, and reside in the building materials. What we did was we exposed six different building materials, including drywall, painted drywall, and then a piece of granite slate floor, a wood floor, and carpet. And then we also wanted to include an example of an impervious surface. So we included an aluminum plate, which theoretically would have no pores inside the material. In order to simulate this wildfire smoke, we burned pine needles and soaked each building material in the wildfire smoke for 40 minutes, and then analyze the re-emission.

Cain: Great. Uh, so tell me a little bit about, uh, what you found. 

Hurley: First and foremost, the material porosity mattered in determining this remission rate of the different VOCs from each material. And so, porosity is pretty much the volume or empty space inside of a material, and for the more porous materials. What we saw is that there was a slower re-emission, indicating that they had this capacity to absorb a larger amount of VOCs and then re-emit them over a longer period of time. So comparing to the impervious aluminum surface, the carpet, um, re-emitted VOCs at a rate seven times slower. And compared to the impervious surface, the drywall re-emission rate for all VOCs was about four times slower, and for other materials, two to three times slower than the impervious aluminum. So porosity clearly had a strong influence on the re-emission when looking collectively at all VOCs re-emitted from a single material. However, when we looked at the different building materials in isolation and looked at how the properties of the different VOCs influenced the re-emission rate, what we found for each material was actually very different, which was an interesting result that I found. 

Cain: Could you talk a little bit more about that? 

Hurley: Yeah. So what we would expect to find was that volatility would have the strongest influence on the re-emission rate, because the more volatile a compound is, the easier it is or the more likely it is to vaporize into the gas phase. And for some materials like the carpet, we did observe the relationship for the more volatile compound was the shorter the re-emission rate was, and the quicker it could, um, volatilize into the gas phase. But for, for the painted drywall, what we saw was that the more hydrophobic a VOC was the slower the re-emission rate, because what I think happened is these VOCs were more likely to dissolve into this organic layer and be more persistent in the paint layer and take longer to re-emit. 

Cain: You mentioned one of the materials that you were looked at is drywall, um, and there's a lot of factors involved with that. Can you tell me a little bit more about what you found?

Hurley: Yeah. So drywall is typically inside people's homes. You'll have a layer of paint and primer. And then the drywall is comprised of gypsum. And so we wanted to look more closely at the role of adding a paint layer on the VOC re-emission, as well as testing how deep the VOCs could potentially penetrate into the drywall material. So in addition to the drywall and painted drywall re-emission tests, what we did as well was soaking a piece of drywall or painted drywall in the pine needle smoke, and then peeling away the outermost layer and measuring that re-emission to see if the VOCs could penetrate through that outermost layer. And what we saw with the painted drywall especially was very interesting because as I mentioned, the materials that were more hydrophobic were more persistent in this layer and had a longer re-emission time, when we removed the outermost layer and looked at the gypsum beneath, what we saw was that the VOCs that were more volatile actually had a slower re-emission. So what I'm thinking is happening is that the smaller and more volatile compounds are diffusing deeper through this paint layer and into the drywall underneath.

Cain: I think a lot of people would be surprised to know that these compounds can seep through these surfaces like this. Um. I'm wondering what you found when you looked at some of the other materials like the wood flooring or even granite.

Hurley: Yeah, so the granite floor behaved pretty similarly to an impervious aluminum surface because there aren't really any pores inside of the granite. However, the rough surface on the exterior does leave a little bit of space for VOCs to adsorb to the surface, but the remission magnitude was much lower from the slate and re-emission rate much quicker because it couldn't absorba higher capacity of VOCs like the drywall or the very porous and fiber-like carpet. What we found for the wood floor was actually surprising because unlike the painted drywall, the more hydrophilic compounds actually had a slower re-emission rate. However, I would expect it to be the opposite trend because wood is typically treated to be hydrophobic because you do not want water to get inside the material and cause decay. So the results for the wood floor was actually fairly surprising. However, it didn't seem to be quite as porous as the drywall or carpet.

Cain: So you've covered a lot of ground in this research and really uncovered a lot of interesting things here. You mentioned some of the items that surprised you. Were there other aspects of your findings that surprised you?

Hurley: I would say the biggest thing that surprised me was restating that the vapor pressure did not predominantly explain the re-emission of the wildfire source VOCs from these indoor materials because I would expect the volatility to be the primary driver for this behavior. And I was also surprised by the amount of VOCs that these materials were able to absorb in such a short amount of time. We soaked them for 40 minutes in an environmental chamber, and even after 40 minutes, you could really, really smell it. They had absorbed a significant amount of VOCs, which just shows the capacity that these materials have for absorbing wildfire smoke, and of course. If a home is impacted by wildfire smoke, it's not gonna be at the concentrations we soaked them in. But still, I was very impressed by this behavior. 

Cain: It was interesting also that, you know, you would assume that paint and different coverings might, um, help protect against something like this, but what did you find, um, and did that surprise you as well? 

Hurley: Yeah, that's a really good point. That also surprised me in that I thought that the paint would act more as a seal for deeper diffusion, and it did prevent some of the larger, more hydrophobic VOCs from diffusing deeper into the drywall material. But these VOCs could still reside in the paint layer, and it may be just as hard to remove them as from a regular piece of drywall. 

Cain: I'm wondering how you hope that this information can be used, uh, to help lead to better indoor air quality for people in their homes, given that we're seeing, you know, more wildfires and this type of um, activity.

Hurley: Yeah, definitely. I think one of the biggest takeaways is the importance of ventilation even after a wildfire event, because I think we still need more research on how to properly mitigate and remove VOCs from indoor materials, but through ventilation. Even though this may not remove the VOCs from the material sources, it can still drastically improve air quality. So it's important to practice proper ventilation by either opening windows when outdoor air quality is safe, or using air cleaners or your ventilation system in the home if you have one and just maintaining proper clean air quality as much as possible if your home is exposed to wildfire smoke. This research really contributes towards understanding how the indoor environment may contribute to prolonged exposure to wildfire source VOCs, because what this study showed as well as other studies is that these indoor surfaces do matter and do have this great capacity to absorb and store, and then re-emit these volatile organic compounds for extended periods of time after a wildfire event, prolonging your exposure. So knowing that the indoor environment could potentially be a long-term source of wildfire smoke pollution, it's important to focus on proper cleaning and ventilating the indoor environment to maintain proper air quality, even for extended periods of time after a wildfire event. And something else that I think this work could help contribute towards is that there currently are some problems with insurance coverage related to wildfire smoke damage. Because to my knowledge, insurance companies, some may only cover damages to the home that , that you can see or that are physical, such as a burned or charred wall. However, we know that the VOCs are there even though you can't see them. But you can smell them. So I'm hoping that more work like this can help inform future insurance coverage for people who are apprehensive about moving back to their homes because of this prolonged source of wildfire VOCs, because it's very, very expensive to replace all of these smoke damaged materials. So, finding a way to better protect people through their insurance could be a good way to help protect human health. And I think another way that it could be possible to really consider the presence of the indoor VOCs is that I would recommend having low-cost sensors in a home that may measure volatile organic compounds. And these typically only measure total VOCs. They can't distinguish between the types of VOCs and the raw values themselves may not be reliable, but these sensors have been shown to be a good reference point. So seeing how the VOC levels in your home preceding a wildfire, and then for extended periods of time after, comparing those values could be helpful to identify if there is this prolonged VOC persistence in your home.

Cain: This research has really got me thinking a lot about indoor air quality more than I had before, and when you talk about the different surfaces and the different findings, it really had me wondering whether or not you would recommend that home builders or homeowners use certain types of materials based on this research? Or if not, is there anything that, you know, an individual should be doing to protect themselves from, um, exposure to the effect of wildfire smoke indoors, if they happen to find themselves in a situation where that smoke may get inside? 

Hurley: Yeah, this is a great question and I find it a bit tricky to answer because realistically, it's hard to have materials in your home that are non-porous, such as aluminum surfaces or maybe glass. And although you maybe can have those materials, for certain parts of your home, such as a glass dining room table instead of wood, I don't know if there's quite enough information yet to formally make recommendations to people, but rather emphasizing the importance of surface cleaning and how this can remove some of the VOCs stuck in the materials as well as I think it's important to really highlight prevention and preventing the wildfire smoke from infiltrating inside the home in the first place, because this can make a huge difference in maintaining indoor air quality. And preventing this VOC absorption and then prolonged re-emission and exposure. And the US EPA website has a lot of very useful and great information about how to prevent wildfire smoke infiltration in your home, such as by closing windows, ceiling cracks in your building envelope, as well as, um, certain ways to maintain your personal heating and ventilation system in order to prevent leakage of outdoor air.

Cain: So what's next for this research? 

Hurley: Yeah, so what I really wanna look at next is the impacts of environmental conditions on this behavior, because if you have a home with wildfire smoke infiltration, let's say in Los Angeles, where it's very, very dry, versus the southeast United States where it's very humid, that humidity might play a role as well as temperature. So really incorporating temperature and relative humidity into a more comprehensive model to model this re-emission behavior. Also, considering the material type as well as the properties of the VOCs. And I'd also like to take this research more into the field and engage with impacted community members and really look at how human behaviors and their air cleaning behaviors during wildfire smoke events may impact indoor air quality so we can really better understand how human behavior and mitigation behaviors can be used to prevent indoor wildfire, smoke infiltration and this VOC absorption and really help to better protect individuals and their homes from this happening.

Cain: When you talk about the air cleaning techniques, is that like, um, people using, uh, air purifiers for example, in some scenarios and what the impact would be in those settings versus a home that's not using that type of technology?

Hurley: Yeah, definitely. So different types of air cleaners that people can use. You can purchase them online or there are some great resources for, um, do it yourself air cleaners. And for these air cleaners, it's important to, if you're worried about volatile organic compounds, to use those with activated carbon. As these remove the VOCs, while the other types of filters only really remove the particulate matter, which is much larger than the volatile organic compounds.

Cain: It'll be exciting to see where your research leads you next. What are you most excited about in terms of, uh, you know, pursuing this topic? 

Hurley: Yeah, I'm really looking forward to, in the future, engaging with impacted community members, and I find that my research is one small piece in a large puzzle of different researchers and communities coming together to really combat this problem associated with the increase in wildfires and wildfire smoke. I had just read an article earlier today about a community in the southwest Oregon, where community members are coming together to conduct prescribed burns. And these can be helpful in preventing catastrophic wildfire events. And moreover, many communities are hosting educational programs and teaching community members how to design effective, do it yourself, air cleaners. And I think with more cooperation and education among these communities, we can really learn how to protect people from wildfire smoke, and I hope that my research can shed some light on the implications of the prolonged exposure and how to prepare your home to reduce this infiltration. And that's what I wanna look at more in the future is how can we more effectively clean these surfaces and what behaviors can help to mitigate this infiltration of wildfire source VOCs into the home so that we can preserve healthy indoor environments that can help protect people from wildfire smoke.

Cain: I appreciate your dedication to this important work. I am really hopeful that it will lead to healthier communities, and I know that it's, uh, already helping shed light on, uh, the impacts of wildfire smoke that maybe people hadn't thought about. Uh, Rachel, thanks so much for taking the time to talk with me about your research.

Hurley: Yeah. Thank you very much for having me. 

Cain: Rachel Hurley is a PhD candidate in WPIs, Department of Civil, Environmental, and Architectural Engineering. 

You can learn more about civil, environmental, and architectural engineering research and academic programs by visiting our website – WPI-dot-edu.

While you’re there, search “wildfires” to read our explainer with answers to frequently asked questions about wildfires.

This has been The WPI Podcast.

Don’t miss our earlier episode on this topic. 

We spoke with WPI fire protection engineering researchers who study how wildfires start and spread.

You can find the conversation on our podcast page at wpi.edu/listen.

There, you can also find audio versions of stories about our students, faculty, and staff -- everything from events to academic projects.

Please follow this podcast and check out the latest WPI News on Spotify, Apple Podcasts, Amazon Music, Audible, or Youtube Podcasts. You can also ask Alexa to “Open W-P-I.” 

This podcast was produced at the WPI Global Lab in the Innovation Studio.

I had audio engineering help today from PhD candidate Varun Bhat.

Tune in next time for another episode of The WPI Podcast.

I’m Jon Cain.

Thanks for listening.