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Environment
Jun 05, 2026
Analyzed by GPT OSS 120B

Wildfire Smoke Undermines US Ozone Gains, Study Shows

AI Summary
A new study published in *Science* finds that since 2015 wildfire smoke has reversed years of progress in reducing ground‑level ozone across the United States, contributing to hundreds of premature deaths annually. The research links the plateau in ozone improvements to rising emissions from increasingly frequent and intense fires, highlighting a looming public‑health challenge.

Study Reveals Wildfire Smoke Reverses Ozone Progress Since 2015

The research team, led by Weizhi Deng and colleagues, analyzed satellite data, EPA monitoring records, and meteorological inputs with deep‑learning models. They discovered that the United States shifted from a decline of 0.65 ppb per year in ground‑level ozone before 2015 to an increase of 0.13 ppb per year afterward, effectively erasing a decade of air‑quality gains.

Quantifying the Ozone Trend Reversal and Associated Mortality

  • Ozone trend change: from -0.65 ppb/yr to +0.13 ppb/yr after 2015.
  • Estimated excess premature deaths: 318 deaths per year in the U.S. since 2013.
  • Global projections: up to 1.4 million annual deaths worldwide by 2100 if wildfire emissions continue unchecked.
  • U.S. forecast: > 70,000 premature deaths per year by 2050 at current fire rates.

Implications for US Air Quality Policy and Public Health

The findings expose a critical gap in current regulatory strategies that focus on reducing anthropogenic ozone precursors from cars, refineries, and industry. Even as those emissions fall, wildfire‑derived carbon monoxide and other gases fuel ozone formation, causing surface ozone levels to plateau. With EPA monitoring stations covering only about 2% of continental U.S. land, the study underscores the need for broader observation networks and integrated climate‑fire‑air‑quality policies.

Future Outlook: Climate‑Driven Fires Threaten Air Quality Gains

Continued global warming is expected to intensify fire frequency and severity, especially in the western United States and Canada. Mitigation measures—both climate‑change mitigation and proactive fire‑prevention—are essential to restore the downward trajectory of ozone and protect public health. Without decisive action, the United States risks losing decades of progress in air‑quality standards and facing escalating health costs linked to ozone and particulate‑matter exposure.