Wildfire smoke accounted for up to half of all health-damaging small particle air pollution in the western U.S. in recent years as warming temperatures fueled more destructive blazes, according to researchers at Stanford University and the University of California at San Diego.
Even as pollution emissions declined from other sources, including vehicle exhaust and power plants, the amount from fires increased sharply.
“From a climate perspective, wildfires should be the first things on our minds for many of us in the U.S.,” said Marshall Burke, an associate professor of earth system science at Stanford and lead author of the study.
Nationwide, wildfires were the source of up to 25% of small particle pollution in some years, the researchers said.
“Most people do not see sea-level rise. Most people do not ever see hurricanes. Many, many people will see wildfire smoke from climate change,” Burke added. The study was published in the Proceedings of the National Academy of Sciences.
The researchers used satellite images of smoke plumes and government air quality data to model how much pollution was generated nationwide by fires from 2016 to 2018 compared to a decade earlier.
An Associated Press analysis of data from government monitoring stations found that at least 38 million people in California, Oregon, Washington, Idaho and Montana were exposed to unhealthy levels of wildfire smoke for at least five days in 2020. Smoke particles from those wildfires were blamed for health problems ranging from difficulty breathing to a projected spike in premature deaths, according to health authorities and researchers.
