HUMAN-CAUSED FIRES TIED TO 20K EARLY DEATHS IN ’18

Small-particle pollution from smoke cited

In 2018, fires raged throughout the nation — and their victims weren’t just those who perished in the flames. New research attributes 20,000 premature deaths in the United States that year to small smoke particles in the air from human-caused fires.

The study, published last week in the journal Environmental Research Letters, looked at human-ignited wildfires and agricultural fires, which are used to manage vegetation on farms. Researchers used data from the U.S. Forest Service’s database, which collects information on the location of fires, their dates, and details about their containment and causes. They then simulated the emissions of the fires in 2003 and in 2018, a particularly active fire year.

Fires belch out fine particulates known as PM2.5. These tiny particles are 2.5 microns or smaller in width — about one-thirtieth the width of a strand of hair. That means they’re small enough to be inhaled deeply into the lungs, and for that reason they are the riskiest particles to human health, the Environmental Protection Agency says.

In the past two decades, more than 80 percent of smoke in the United States was human-caused, the researchers found. In 2018, human-caused fires accounted for more than 67 percent of all PM2.5 emissions.

Agricultural fires were more common in the Southeast, while human-sparked wildfires dominated in the West and caused large swaths of smoke pollution. This was especially true in California, where levels of PM2.5 smashed recommended thresholds during the Camp and Mendocino Complex fires.

The scientists looked at the estimated population exposed to PM2.5 and linked that data with other research on how smoke exposure contributes to early deaths. Overall, they attributed 20,000 premature deaths to humansparked fires in 2018 and 7,400 to 2003 fires.