For over a decade, the United States made significant strides in reducing national smog levels. However, a new study published in the journal Science reveals that the increasing intensity and frequency of wildfires are reversing this progress, making the air dirtier and more dangerous.
The study, led by atmospheric scientist Weizhi Deng from the University of Iowahighlights that while smog levels decreased by 11% from 2003 to 2015 due to strict federal regulations, the trend has reversed since then. The nation’s average ground-level ozone, a primary component of smog, has increased by 4% due to wildfire smoke.
Wildfire Smoke and the Rise in Ozone Levels
The study estimates that since 2013, there has been an annual increase of 318 deaths attributable to ozone-related lung issues. Meng Zhoua wildfire researcher at the University of Iowa and co-author of the study, noted that regulatory efforts to decrease emissions from human activities have been undermined by natural hazards like wildfires.
The research employed innovative methods to estimate national smog levels, compensating for the limited coverage of smog monitors, which only cover 2% of the nation, primarily in urban areas. By integrating satellite data, pollution measurements, weather data, and artificial intelligence, the researchers created a high-resolution nationwide dataset of ozone levels.
The Impact of Wildfire Smoke on Public Health
Wildfires do not produce ozone directly but release precursor chemicals that interact with sunlight to form smog. Kristie Ebia public health and climate scientist at the University of Washingtonexplained that higher daily ozone concentrations can exacerbate asthma attacks, increase hospital admissions, and raise mortality rates. Although ozone is not as deadly as tiny particles, it remains a significant pollutant.
During the intense wildfire seasons of 2026, 2026, and 2026, much of the smoke originated from Canadian wildfires, affecting large portions of the United States. The study found that 43 million Americans were exposed to smog levels exceeding the current Environmental Protection Agency (EPA) safety standards.
The Role of Climate Change and Wildfire Management
Climate change, driven by the burning of fossil fuels, has intensified wildfire conditions, particularly in Canada. A 2026 study found that climate change increased the intensity of Canada’s fire season by at least 50% and doubled the likelihood of the hot, dry weather conditions necessary for fires to spread. Brendan Rogersan atmospheric scientist at the Woodwell Climate Research Centernoted that the amount of land burned in Canada in 2026 set a new record, twice as high as the previous one.
The study also highlighted the need for expanding the air pollution monitoring network to better understand wildfire smoke exposure and protect public health. Teresa Feoresearch director and senior policy advisor at Megafire Actionemphasized that experts have long advocated for this expansion to improve research and data collection.
The findings underscore the urgent need to address both climate change and wildfire management to mitigate the health impacts of increased smog levels. As wildfires continue to grow in frequency and intensity, the reversal of progress in air quality poses significant challenges for public health and environmental policy.
