As wildfires surge in both size and frequency across the Western United States, their impacts extend far beyond the immediate devastation of flames and charred landscapes. Recent research spearheaded by a multidisciplinary team from leading institutions in Colorado, Utah, and California has revealed a troubling secondary consequence of these infernos: a marked increase in harmful ozone levels throughout the affected regions. Published in the prestigious journal Atmospheric Environment, the study uncovers how the complex chemistry of wildfire smoke actively generates ozone, a potent pollutant with serious implications for public health and climate change.
The focal point of this groundbreaking study revolves around massive wildfires that scorched vast areas of the Western U.S. in the summer of 2020. Between August 15 and 26, over one million acres were engulfed by fire across seven northern California counties alone, triggering unprecedented economic damage estimated at $12 billion. Simultaneously, large fires such as Utah’s East Fork blaze and Oregon’s Lionshead and Beachie Creek fires ravaged hundreds of thousands more acres. While the immediate effects of these fires—smoke, ash, and destruction—are visible and well-known, this research peels back the veil to examine the invisible chemical transformations occurring high above the infernos.
Central to these discoveries is the work of Jan Mandel, a mathematics professor emeritus at the University of Colorado Denver, whose expertise in applied and computational mathematics was key to modeling the wildfire chemical emissions and their interactions within the atmosphere. Mandel’s sophisticated approach integrates atmospheric chemistry with advanced weather prediction software, allowing the research team to simulate the processes by which wildfire-derived compounds, under sunlight, react to form ozone far from their source. This coupling of fire dynamics with atmospheric chemistry models represents a significant technical achievement in understanding wildfire pollution.
Wildfires release a complex mixture of volatile organic compounds (VOCs) and nitrogen oxides (NOx), the precursors necessary for ozone formation through photochemical reactions. However, unlike direct emission of ozone, smoke acts as a chemical incubator where these precursors undergo transformations driven by solar radiation. This distinction not only challenges traditional assumptions about wildfire emissions but also complicates efforts to predict ozone surges during wildfire events. By simulating these processes across broad spatial scales, the study fills critical gaps in capturing the interaction between fire behavior, pollutant chemistry, and meteorological conditions.
Quantifying the magnitude of this effect, the research finds that ozone levels increase by an average of 21 parts per billion (ppb) across the impacted regions during wildfire episodes. This increase is superimposed on already elevated ozone baselines prevalent in the Western United States, often pushing concentrations beyond the 70-ppb threshold established by the U.S. Environmental Protection Agency (EPA) as a health standard. Elevated ozone levels are not only detrimental to respiratory health, causing symptoms from coughing to chronic cardiovascular stress, but they also exacerbate climate warming due to ozone’s role as a short-lived but powerful greenhouse gas.
The study’s computational simulations leveraged the Weather Research and Forecasting model with Chemistry (WRF-Chem), a state-of-the-art coupled atmosphere-chemistry model, fine-tuned with wildfire fire behavior data. This integration enabled unprecedented spatiotemporal resolution in tracking how fire emissions disperse, react, and impact air quality on regional scales. Importantly, it allowed the researchers to attribute spikes in ozone concentrations specifically to wildfire smoke, distinguishing them from other anthropogenic and natural pollution sources.
The collaborative nature of this research is noteworthy as it unites expertise from several prestigious institutions. Alongside Mandel, Derek Mallia, a research assistant professor at the University of Utah with extensive experience in wildfire modeling, led the simulation efforts. Adam Kochanski, an associate professor at San Jose State University, also contributed vital insights from his long-standing work on fire-atmosphere interactions. Supporting these senior researchers, the research team included emerging scholars such as Cambria White, an undergraduate student, and postdoctoral researchers affiliated with the Wildfire Interdisciplinary Research Center, drawing from a rich blend of scientific backgrounds.
Financial and logistical support from agencies such as the Utah Division of Air Quality, NASA’s FireSense Project, and the University of Utah’s Wilkes Center for Climate Science & Policy underscored the strategic relevance of this work. Their funding facilitated high-performance computing resources essential for running such computationally intensive simulations, as well as enriching interdisciplinary dialogue necessary to translate complex atmospheric chemical phenomena into actionable environmental insights.
In addition to its scientific contributions, the study serves as a clarion call for public health authorities and policymakers. The linkage between wildfire smoke and increased ozone concentrations amplifies the urgency to mitigate wildfire risks, improve air quality monitoring, and strengthen public advisories during wildfire seasons. Regions prone to wildfire smoke must prepare for compounded health threats, particularly among vulnerable populations such as those with pre-existing lung or heart conditions.
Jan Mandel’s storied career embodies the convergence of mathematics, computational science, and practical problem-solving. With nearly two hundred published articles and a pedigree spanning numerical mathematics to aerospace applications, Mandel’s computational models have proven versatile and impactful. His work on wildfire emissions simulation builds upon this foundation, exemplifying how mathematical rigor and interdisciplinary collaboration can drive breakthroughs in understanding environmental crises.
The researchers emphasize that wildfires’ contribution to ozone pollution is often underestimated, partly because ozone is not a direct emission product of combustion. It emerges through a cascade of photochemical reactions far from the burning site, which complicates real-time detection and attribution. By integrating fire behavior with atmospheric dynamics and chemistry, this study paves the way for more accurate predictive models that can better inform both firefighting strategies and public health responses.
Finally, the research highlights the growing interplay between climate change and public health, where the rising prevalence of wildfires driven by warming temperatures further inflates ozone levels. These compounded effects risk creating a feedback loop of escalating air quality degradation and health issues, accentuating the importance of scientific research that can guide mitigation policies. Understanding and forecasting the chemical legacy of wildfires will be vital as societies confront the twin challenges of environmental change and human well-being.
Subject of Research: Not applicable
Article Title: Simulating the impacts of regional wildfire smoke on ozone using a coupled fire-atmosphere-chemistry model
News Publication Date: 25-Jul-2025
Web References:
- Atmospheric Environment Journal
- Weather Research and Forecasting Model with Chemistry (WRF-Chem)
- U.S. Environmental Protection Agency Ozone Standards
- Colorado Department of Public Health – Ozone Pollution and Your Health
- NASA FireSense Project
- University of Utah Wilkes Center
References:
Derek Mallia, Jan Mandel, Adam Kochanski, et al. “Simulating the impacts of regional wildfire smoke on ozone using a coupled fire-atmosphere-chemistry model.” Atmospheric Environment, 25 July 2025. DOI: 10.1016/j.atmosenv.2025.121404
Image Credits: Photo credit: Brian Maffly
Keywords: Air pollution, Wildfire smoke, Ozone formation, Atmospheric chemistry, Computational modeling, Environmental health, Climate change
