Wildfires are destroying decades of clean air efforts in the U.S.

Increases in wildfire smoke are reversing decades of improvements to air quality in some parts of the U.S., according to new research.

Increases in wildfire smoke are reversing decades of improvements to air quality in some parts of the U.S., according to new research led by Stanford University and published Wednesday in the scientific journal Nature. 

Scientists evaluated more than two decades of satellite and air monitoring data to assess the concentration of tiny particles within wildfire smoke and how they affected air quality. The research finds that wildfire smoke is a growing source of pollution the U.S. is struggling to control. 

Wildfire smoke made an imprint on pollution trends in three-quarters of all U.S. states, the research found. 

In those states, “wildfires have undone 25% of previous progress” that resulted from the Clean Air Act, said Marshall Burke, an associate professor at Stanford University and the study’s lead author. “In half a decade, we’ve ripped out really a lot of the progress we’ve seen over multiple decades before.” 

The research comes as wildfires have made headlines across the U.S., killing at least 97 people in Maui, Hawaii, in August and blanketing the East Coast with smoke in June. This year qualifies as the worst year on record for wildfire smoke exposure per person in the United States.