Wildfires Undermine US Ozone Gains, Study Warns
WHO:
ABC News - Weizhi Deng, atmospheric scientist at the University of Iowa, is the lead author of the study.
ABC News - Meng Zhou, wildfire researcher at the University of Iowa, is a co-author of the study.
ABC News - Cristina Archer, environment professor at the University of Delaware, commented on the study.
ABC News - Teresa Feo, Megafire Action policy director, emphasized the need for expanded air pollution monitoring.
ABC News - Dr. Lynn Goldman, former dean of the George Washington University School of Public Health, criticized the EPA's standards.
ABC News - Brendan Rogers, atmospheric scientist at the Woodwell Climate Research Center, discussed the record land burned in Canada.
ABC News - Lixu Jin, atmospheric scientist at Rutgers, commented on climate change's impact on wildfire intensity.
ABC News - Gina McCarthy, former EPA Administrator, expressed concern over eroding smog improvements.
WHAT:
ABC News - A study found that smoke from larger wildfires is reversing over a decade of improvements in U.S. smog levels.
ABC News - The national smog level dropped by 11% from 2003 to 2015, but since 2015, ground-level ozone has increased by 4%.
ABC News - The study estimates an increase of 318 American deaths per year since 2013 due to ozone-related health issues.
ABC News - The average amount of U.S. land burned by wildfires each year is now 9% higher than from 2003 to 2014.
ABC News - In 2023, the amount of land burned in Canada was a record, two times higher than the previous record.
ABC News - Smoke from Canadian fires in 2023 killed 82,100 people globally, including 33,000 in the United States.
WHERE:
ABC News - The study indicates that the biggest increase in ozone levels occurred in the Northern Rockies and the Midwest.
ABC News - 43 million people in the U.S. were exposed to smog levels exceeding the current EPA safety standard during heavy wildfire smoke seasons.
WHEN:
ABC News - The study was published in the journal Science.
ABC News - The Biden administration delayed plans to tighten air quality standards in 2023.
ABC News - The wildfires in Canada were particularly severe in 2022, 2023, and 2024.
WHY:
ABC News - Climate change is cited as a significant factor contributing to the increase in wildfire intensity and frequency.
ABC News - Wildfires release precursor chemicals that contribute to smog formation when they interact with sunlight.
HOW:
ABC News - The study used artificial intelligence to create a nationwide dataset of ozone levels, compensating for the limited number of smog monitors in the U.S.
(UPDATED June 4, 2026 19:42 UTC)
A new study reveals that smoke from larger wildfires is reversing over a decade of improvements in U.S. smog levels, with ground-level ozone rising by 4% since 2015 after a previous drop of 11% from 2003 to 2015. The research, led by Weizhi Deng from the University of Iowa, estimates that since 2013, ozone-related health issues have contributed to an increase of 318 American deaths each year, with 43 million people exposed to smog levels exceeding current EPA safety standards during heavy wildfire smoke seasons. The study highlights the significant role of climate change in increasing wildfire intensity and frequency, as well as the need for expanded air pollution monitoring, especially in regions like the Northern Rockies and the Midwest.