Ask a professor: Julia Rager on urban wildfire risks
February 13, 2025
Dr. Julia Rager
People may associate wildfires with undeveloped forests and lands, but the recent fires in Southern California ravaged developed areas, consuming homes and buildings in neighborhoods and forcing evacuations in heavily populated areas. Wildfires in either setting pose many safety and health risks, both immediate and long-term. Among them is exposure to toxicants released from burned materials.
At the UNC Gillings School of Global Public Health, Associate Professor Julia Rager ’13 (PhD) works to identify chemicals that are released into the air in wildfire smoke and the associated health risks for people who are exposed.
Can you describe your research to understand emissions from wildfires in more urban and suburban settings?
RAGER: I’ve been working on wildfire toxicity assessments for several years, and there is plenty to study and think about just investigating wildland fires. But it is also important to look at what’s called the wildland-urban interface, which is where development meets wildland. Those areas are very close to where wildfires might begin, and there has been a lot of coverage of this with the Palisades fires. Understanding exactly what burns there and evaluating and quantifying health risks attributable to those kinds of exposures is extremely understudied.
We’re trying to fill that gap with controlled, lab-based scenarios so we can know what actually burns there and evaluate the toxicity potencies resulting from different exposure scenarios to understand what happens when things like homes burn and the resulting health impacts. We are trying to learn what materials are the most toxic and the most combustible, and from there hopefully we can help inform choices about what materials are best for homes and buildings in wildfire-prone areas.
What does that look like in the lab? Are you taking things like PVC and drywall and lighting them on fire?
RAGER: Yes, we’re first figuring out what is in an average U.S. home and then we buy those materials. We’re up to a list of 60 different materials, whether it’s PVC pipes, walling materials, general household clutter or anything you can think of that’s in a home. And then we grind them up and burn them.
We capture the smoke and stabilize it with what’s called a tube furnace system. We have controlled burn scenarios at whatever temperature we want for however long we want. And it’s hooked up to a series of impingers that collect volatile and semi-volatile compounds that are emitted and stabilize them in a solvent. Once it’s captured and stabilized, you can do toxicity assessments, chemistry assessments or any other test you may be interested in.
What are you learning?
RAGER: We have more data on wildland fires, but we can tell you that there’s a lot of variability in the relative toxicities of whatever gets burned, and it relies upon the substance that you’re burning and the combustion conditions. So flaming produces different chemistries than a smoldering condition that’s more sustained. And things like metals might be emitted at higher concentrations during the flaming period, but other types of compounds are emitted during smoldering conditions.
In terms of health outcomes, we’re seeing a lot of similarities in the toxicological response profiles to different human disease profiles across the pulmonary system, specifically including things like asthma and significant perturbations of infectious disease responses that make you more apt to get infections, like COVID-19 and other respiratory infections after exposures. Learning about those types of health outcomes is then prioritized in future toxicological and epidemiological assessments.
What are some precautions people who live in an area close to a fire can take?
RAGER: We’re still studying this as well, and it’s a tricky issue. Probably the easiest thing that you could do is make sure that you have a home air filtration system that’s up and running and clean, and to maybe even get systems-level redundancies in your air filtration systems by getting some box filters that are deployable, especially in communities that have these kind of sustained smoke conditions that have been happening over the past few weeks. (Note: this video shows how to make a DIY air cleaner box.)
We’re looking into other things, like figuring out which type of masks are the best at filtering smoke particulate matter and gases. I can’t speak to which air masks we would recommend at this point, but that is something that researchers are studying.
Rager was a 2024 recipient of the Phillip and Ruth Hettleman Prize for Artistic and Scholarly Achievement, which recognizes junior faculty members who demonstrate groundbreaking and innovative research along with future career promise. Privately funded awards like the Hettleman Prize help Carolina support professors whose research will benefit the state of North Carolina and the world.
As told to Drew Guiteras
Read the full story on Carolina Stories.
Contact the UNC Gillings School of Global Public Health communications team at sphcomm@unc.edu.
