Air quality alerts went into effect in 11 states this week, as wildfire smoke from Canada as well as Central California’s Gifford Fire — which has burned nearly 100,000 acres and is just 15 percent contained — spread across the United States. As the planet warms, such blazes are burning more intensely, billowing smoke that can travel thousands of miles. In July, a group of Republican members of Congress went so far as to write an official letter of complaint to Canada, arguing that the country’s smoke is making it difficult for Americans to enjoy summer. But a growing body of research is reinforcing the knowledge that wildfire smoke is much more than an inconvenience — in fact, wildfire smoke is far deadlier than the flames themselves.

New research on the fallout of the Palisades and Eaton fires that ravaged Los Angeles in January bears this out. Officially, the conflagrations killed 30 people. But the new study suggests that’s a significant underestimate, because it isn’t factoring in the victims who may have died miles away from the flames as toxic smoke wafted over the landscape. These researchers estimate the death toll may be closer to 440 — or higher.

That’s “a big difference between what was officially recorded versus what we estimate based on our mortality modeling,” said Andrew C. Stokes, a mortality demographer at the Boston University School of Public Health, co-author of the research letter describing the findings in the Journal of the American Medical Association. “Los Angeles has a strong death investigation system, and yet it’s still very difficult for the medical examiners and coroners to accurately assign cause of death during a natural disaster.”

The researchers found the additional deaths by looking at mortality data from the National Center for Health Statistics at the Centers for Disease Control and Prevention, demonstrating that wildfire smoke is deadlier than recorded in official death counts. From this they could see how many people died in Los Angeles County in 2018, 2019, and 2024 — that is, how many Angelenos typically pass away in a given year. (They skipped 2020 through 2023, because those years were not typical, given deaths from the Covid-19 pandemic.)

Read the full article about the deadly toll of wildfire smoke by Rebecca Egan McCarthy and Matt Simon at Grist.