A University of Utah-led study shows wildfire smoke can significantly increase ozone levels, posing severe health risks.
New research conducted by the University of Utah, in collaboration with San Jose State University and the University of Colorado Denver. has revealed a hidden danger lurking in wildfire smoke, one that significantly increases ozone levels and poses severe public health risks.
This study, published in the journal Atmospheric Environment, sheds light on how wildfire smoke can exacerbate ozone pollution to levels that surpass federal health standards.
“The question I wanted to ask was, if we don’t have urban emissions, let’s say that we zero out all emissions, will we still have an ozone problem?” lead author Derek Mallia, a research assistant professor of atmospheric sciences at the University of Utah, said in a news release. “This study suggests that we could remove all of the regional emissions from anthropogenic sources of NOx, but fires can still produce a large amount of ozone.”
Double Dose of Air Pollution
The research highlights the dual threat posed by wildfire smoke: it not only results in significant emissions of fine particulate matter but also increases ozone concentrations.
Mallia’s team utilized coupled computer models, WRF-Sfire and WRF-Chem, to simulate a record-setting smoke event in 2020, a year marked by some of the most severe wildfires in modern U.S. history.
During the period of August 15-26, 2020, the Western United States experienced devastating fires, including California’s August Complex fire which burned over 1 million acres. The study found that wildfire smoke increases ozone concentrations by an average of 21 parts per billion (ppb).
“Ozone was roughly 20 to 30% higher because of wildfire smoke,” Mallia added. “That’s pretty big.”
The Intricacies of Ozone Formation
Ozone formation is a complex process that occurs when oxygen atoms from other pollutants recombine through a photochemical reaction driven by sunlight.
The primary drivers of this reaction are nitric oxides (NOx) and volatile organic compounds (VOCs), the latter being major components of wildfire smoke.
While NOx is more commonly associated with human activities such as vehicle emissions and industrial processes, the study illustrates that even in remote areas with few anthropogenic sources, wildfires can still drive significant ozone pollution.
Further complicating the scenario is the fact that smoke can also shade sunlight, which can reduce the rate of ozone formation.
“You also have a lot of particulate matter, which is a pollutant, too, but it can block sunlight and therefore that will reduce the amount of sunlight available for ozone photochemistry. It can be substantial in some cases,” Mallia added. “If you’re right over the fire, there’s usually enough smoke shading where it limits the amount of ozone. But if you get far enough away and the plume becomes relatively diffuse, it’s usually not thick enough to really limit ozone.”
Implications for Air Quality Management
The study’s key takeaway is the urgent need to refine existing models to better predict and manage air quality. As wildfires become more frequent and severe due to climate change, tools like WRF-Sfire and WRF-Chem are essential for forecasting air quality during wildfire seasons.
However, these tools require continuous improvement to handle the complex dynamics of wildfire smoke.
The study called for enhanced predictive models to aid public health officials in issuing accurate advisories and mitigating potential health hazards.
Source: University of Utah