Understanding wildfire smoke

At the time of the fire, Chou was a high school junior living in Cupertino, Calif. Despite being more than 200 miles from the epicenter of the fire, smoke was heavy in her community. Chou’s school remained open, and she and many other students walked home from school in the smoke and found themselves coughing badly afterwards.

Fires like the Camp Fire and the recent fires in Los Angeles are called wildland-urban interface wildfires, because they burn across forest areas and urban development. These fires are different from those that happen on undeveloped land, because the burning of homes and other structures adds many additional chemicals and heavy metals into the smoke’s composition.

Fires like the Camp Fire and the recent fires in Los Angeles are called wildland-urban interface wildfires, because they burn across forest areas and urban development.

As wildfires become more common in the United States, it’s important to understand the health implications for those who inhale wildfire smoke. This is particularly true of wildland-urban interface wildfires, since 39% of all American homes are located in the wildland-urban interface.

“All of these additional materials going into a wildfire changes the toxicity of smoke,” said Chloe Chou, who now works in the lab of Associate Professor Julia Rager, PhD. “But up until now we have only been able to make predictions about its chemistry and many of its health impacts using studies focused on wildfires that only burn trees. Wildland-urban interface fires haven’t been modeled and measured in a lab setting yet.”

“All of these additional materials going into a wildfire changes the toxicity of smoke.”

– Chloe Chou

Chou and the team in Rager’s lab are trying to change that. They have compiled a list of 60 materials that are found in the average American home, including construction materials, appliances, clothing, household chemicals and general clutter such as knick-knacks. These items are currently being ground down to a fine particle that will then be burned in a furnace where the smoke can be analyzed.

“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,” said Rager, who is an associate professor in the Department of Environmental Sciences and Engineering.

“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.”

– Julia Rager

Rager’s lab is working in partnership with the Environmental Protection Agency, which will perform the tests to analyze the smoke’s composition and toxicity levels.

“The more information we can gather about these fires, the more we’ll know about how to treat them,” said Chou. “My hope is that our research can help guide policy around wildfire response.”

While much is still unknown about wildfire smoke, particularly from fires at the wildland-urban interface, it’s clear that inhalation of wildfire smoke has a negative health impact.

Radhika Dhingra, adjunct assistant professor in the Department of Environmental Sciences and Engineering and current student in the East Carolina University Brody School of Medicine, has also studied air pollution extensively, with a focus on its health effects.

“Most of the research on wildfire smoke so far has looked at short-term health implications and acute events like hospitalizations for asthma in the immediate aftermath of a fire. But we still have a lot to learn about the long-term health effects of inhaling wildfire smoke,” said Dhingra.

When it comes to air pollution from wildfire smoke, Dhingra’s research has primarily focused on how exposures during gestational and early-life development affect later-life respiratory health. While her research didn’t indicate a strong signal that exposure during the gestational period affected health long-term, it did find a link between exposure to wildfire smoke in the first six months of life and the chronic need for lower respiratory medications, such as inhalers or nebulizers, as well as an earlier need for such medications.

“Wildfire smoke is a form of air pollution, and like with air pollution, we know that everybody who inhales it will be impacted,” said Dhingra. “Certain groups – like the very young, the elderly, pregnant women and those with cardiovascular disease – are at the greatest risk, but we still have a lot to learn about the long-term health impacts of wildfire smoke exposure.”

“Wildfire smoke is a form of air pollution, and like with air pollution, we know that everybody who inhales it will be impacted.”

– Radhika Dhingra

There are many challenges to quantifying the impact of wildfire smoke. Beyond toxicity variations depending on what’s burning, wildfire smoke is heavily impacted by geography and meteorology, and health impacts also vary based on individual factors like stress levels and if those inhaling smoke have any underlying health conditions. As wildfires become more common, Gillings School researchers will continue working to protect the public from this growing threat.