As wildfires increasingly encroach on communities at the wildland-urban interface (WUI), new research suggests that burning homes may introduce additional air quality hazards beyond those of traditional forest fires.
A study led by scientists at the Cooperative Institute for Research in Environmental Sciences (CIRES) found that synthetic materials commonly used in residential construction— such as plastics and insulation — can release elevated levels of harmful compounds when burned. The findings were published in the journal ACS Environmental Science & Technology.
“Urban fires are becoming more prevalent,” said William Dresser, a CIRES research scientist and lead author of the study, pointing to recent disasters such as the Marshall Fire in Colorado and the Lahaina fires in Hawaii. “There are emerging questions from an air quality standpoint of how these types of fires change exposures.”
To better understand these risks, Dresser collaborated with CIRES Fellow Joost de Gouw and researchers from Colorado State University. The team conducted controlled laboratory burns of 18 common building materials, capturing and analyzing emissions in real time.
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Their analysis focused on volatile organic compounds (VOCs), a group of carbon-based chemicals known to impact both air quality and human health. The researchers observed heightened levels of hazardous VOCs, including benzene and styrene, when synthetic materials were burned. Both compounds are associated with an increased cancer risk.
The study also identified less-understood emissions, such as molecular fragments derived from nylon polymers, highlighting gaps in current knowledge about the full range of pollutants released during structure fires.
However, the researchers emphasize that synthetic materials represent only a small portion of a home’s overall mass. Wood and timber products remain the dominant building materials, and their emissions more closely resemble those from natural vegetation fires.
To assess real-world impacts, the team modelled emissions from a full house fire using typical building material compositions. These results were then compared to emissions from structural wood fires and a natural Douglas fir forest fire.
While whole-house fires did show elevated levels of certain toxic VOCs — particularly benzene and styrene — many other emissions were comparable to those produced by wood and forest fires.
“Since synthetic materials are a pretty small part of a home, we found their impact can be muted,” Dresser said. “But it was in part surprising to see the nuanced picture.”
The findings show the growing complexity of wildfire-related air pollution, especially as fires increasingly affect developed areas. According to de Gouw, the research marks an important step toward understanding how structure fires may alter environmental and public health risks.
“Our research shows clearly that some toxic compounds are higher when a home burns, relative to a wildfire,” he said. “Future work is focused on the compounds that end up in ash or can be leached from ash into waterways.”
The authors note that further research is needed to fully assess long-term environmental impacts, particularly as wildfire activity continues to intensify in populated regions.
