NSF NCAR scientists create first national inventory of emissions from structure fires at the wildland-urban interface
February 17, 2026 – Written by Audrey Market
A fire breaks out at the border between the wilderness and the city. (Image: FEMA)
Impact statement: A national understanding of emissions from structure fires lays the foundation for making communities more prepared and resilient to the effects of smoke from urban wildfires. |
A research team led by the National Science Foundation National Center for Atmospheric Research (NSF NCAR) has published a baseline inventory of emissions resulting from fire-destroyed structures at the wildland-urban interface (WUI).
Researchers have previously suspected that fires in WUI regions (where human development meets undeveloped wilderness) may be more likely to produce harmful emissions than forest or grass fires. However, emissions were not quantified.
This new research nature communicationsprovides the first inventory of emissions from structure fires in the WUI region. The results clearly show that structural fires are a major cause of air pollution.
WUI fires are becoming increasingly common in the United States, with more than 100,000 homes destroyed since 2005. Because these fires are concentrated in time and space, they can cause very high levels of local pollution, with important implications for air quality and public health in nearby urban areas.
“We didn’t expect the emissions of some pollutants to be this high because the area burned is very small compared to vegetation fires,” said NSF NCAR scientist Wen-Fu Tang, lead author of the paper. “But if you think about things in your home or office, there are a lot of things that can be harmful to humans if they catch fire. For example, if you burn your smartphone, you don’t want to breathe in the fumes.”
This research was primarily funded by NOAA’s Atmospheric Chemistry, Carbon Cycle, and Climate Program.
Quantification of emissions
Vegetation fires are more widely studied than WUI fires, primarily because they are the most common type of wildfire worldwide. But Tan and his colleagues believe that emissions from WUI fires may have a significant impact due to their proximity to communities and the type of fuel being burned. Air pollutants from burning structures from WUI fires are not included in national emissions estimates, so the team had to devise a way to create an inventory.
Quantifying fire emissions requires three key pieces of information: where the fire started, how much fuel was burned, and the pollutants emitted from the fuel. All this information about structure fires has only recently become available, thanks to a new user-friendly dataset created by researchers at the University of Colorado Boulder. This dataset collects wildfire information from the U.S. National Incident Management System. This made it much easier to determine the location and extent of WUI fires and the number of buildings affected.
The team used this dataset to determine the extent of areas affected by WUI fires in the United States and the number of structures destroyed between 2000 and 2020. The team then used that information to cross-reference the number of affected structures with a dataset called COMBUST, which estimates urban fuels across the United States, to calculate what burned in each fire.
Using numbers from these two datasets, the researchers were able to calculate emissions based on the mass of material burned and the estimated fuel type. The researchers used median pollutant emission factors from previous studies for this calculation. Using this intermediate value means that a precise pollutant can be more or less harmful in a particular location.
“Assuming the emission factors for all structures across the country are the same, it means there is some uncertainty in the numbers,” Mr Tan said. “We hope future studies will make these numbers even more accurate, but even this baseline emissions inventory is critical to understanding the impact these fires have on local communities.”
The researchers found that in wildfires that burn structures, the burning of materials such as plastics, treated wood, wiring and other household items releases more complex and harmful pollutants. The emissions included pollutants ranging from carbon monoxide to hydrochloric acid to lead. Emissions of the type from buildings burned in WUI fires are hazardous to human health. In addition to affecting local air quality, researchers believe pollutants could also enter homes downwind from the evacuation zone, impacting them even more than homes within the fire zone.
The study also found that the 20 most destructive fires accounted for 68% of carbon monoxide emissions from WUI fires. In some states, emissions of certain harmful pollutants exceeded all anthropogenic emissions combined. The convergent effects of several extreme events highlight the importance of improving our ability to predict WUI fires and model their emissions, the researchers said.
“The increasing frequency of large structure fires, especially across the western United States, highlights the need to better understand these fires and their impact on people,” said Kristin Wiedinmayer, UCAR community program director and second author of the paper. “We need to do more research on these types of fires to make our communities safer.”