Crucially, they found a mechanism for predicting the production of the pollutant ozone—which, at the ground level, can create poor breathing conditions and also harm ecosystems. Also, the team found that mixing wildfire smoke with urban pollution ramps up the production of ozone, meaning that wildfires upwind of cities are a recipe for air quality problems.
"Of course it is well known that wildfires lower air quality. But it's important to understand the chemical and physical mechanisms by which they do so that we can more effectively forecast how individual fires will impact the communities downwind of them," says Paul O. Wennberg, R. Stanton Avery Professor of Atmospheric Chemistry and Environmental Science and Engineering.
Wennberg is a corresponding author of a paper on the research that was published by Science Advances on December 8.
The paper draws on data collected through the NASA/NOAA FIREX-AQ project, which spent
a month flying missions out of Boise, Idaho, during the summer of 2019. (The project later studied agricultural fires in the Midwest.) Riding a DC-8 that had been converted into a flying laboratory, scientists flew through smoke plumes and gathered information from instruments mounted on the plane. Included in the payload were two instruments from Caltech operated by chemistry graduate students Krystal Vasquez and Hannah Allen, staff scientist John Crounse, and lead author Lu Xu, who completed the work as a staff scientist in Wennberg's lab and is now a research scientist with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder working in NOAA's Chemical Sciences Laboratory.