Wildfire Smoke Could Kill Over 5,000 Californians a Year By 2050, Study Shows

If the planet continues to warm at the current rate, smoke from wildfires will kill as many as 70,000 Americans a year by 2050, according to new research from Stanford University.

The research, published Thursday in the journal Nature, found that wildfire smoke is already killing around 40,000 people a year in the U.S.

The study is some of the strongest evidence available suggesting that the harms of wildfire smoke could become among the most dangerous consequences of climate change in the U.S. It contributes to a growing body of evidence demonstrating the link between human-caused climate change and worsening public health outcomes.

Californians are disproportionately at risk due to a substantial increase in wildfire activity in the Western U.S., said Marshall Burke, an environmental economist at Stanford and co-author of the study. The researchers estimate an excess of 5,060 deaths in the Golden State per year, compared to 2011–2020 — deaths that wouldn’t have happened if not for the effects of wildfire smoke.

“Northern California in particular has experienced immense wildfire smoke exposure in the past five to 10 years,” Burke told KQED. “Unfortunately, we project that’s going to increase in the future.”

Decades of research have shown the relationship between a warming climate and more intense, more frequent wildfire activity. In California, this was most evident in the fire season of 2020, which saw more land burned than any year in recorded state history.

“We wanted to understand, what does that mean for the future?” Burke said. “Can we project how changes in wildfire activities and resulting smoke exposure will change under future climate, and can we map that all the way to health impacts, try to understand the health burden?”

Wildfire smoke is so dangerous because it contains fine particulate matter — small particles of ash and soot that can get deep into the lungs and bloodstream.

In many parts of the Western U.S., the particulate matter from wildfire smoke in extreme smoke years has accounted for more than half of all air pollution, the study noted, and has led to reversals of 20-year gains in air quality since the passage of the Clean Air Act.

Other research has found that Indigenous Californians are disproportionately exposed to fine particulate matter from wildfires, experiencing 1.68 times more than expected.

Of course, every year will not be as drastic as 2020, but Burke said the overall trend is clear. The study found that what has played out in the state over the past decade “is likely to increase in the future.”

These deaths will also exact a heavy financial toll, exceeding estimates of climate-caused damages from all other causes in the U.S. combined.

The study pointed to an “urgent need” for wildfire smoke adaptation and mitigation if these damages are to be avoided. Burke recommended forest management strategies like thinning and prescribed burns to reduce the dry vegetation that acts as a fuel for forest fires. Californians, especially those who are more vulnerable to wildfire smoke, can also reduce their exposure and protect themselves by staying indoors on hazy days and using air filters.

“These are projections, not inevitabilities,” Burke said. “There’s a lot that we can do to hopefully make sure they don’t come to pass, that our projections are in fact wrong.”

KQED’s Amanda Hernandez contributed to this report.