Wildfire Smoke Makes Mental Health Conditions Worse Too

By Dave Levitan | April 4, 2025 | 10:15am

Photo by Christopher Michel/Wikimedia Commons

Climate wildfires

Wildfire Smoke Makes Mental Health Conditions Worse Too

The obvious impact of increasingly catastrophic wildfire seasons, beyond just the potential destruction of entire neighborhoods and towns, is on things like asthma, heart disease, and other lung conditions. There is plenty of research demonstrating that PM2.5, the tiny particles found in wildfire smoke and other sources of pollution, make those problems worse and increase hospitalizations, healthcare spending, and more. As a new study demonstrates, the same is true for mental health disorders.

Published on Friday in JAMA Network Open, the new work found that increasing concentrations of wildfire smoke-specific PM2.5 increased hospitalizations for mental health disorders including depression, anxiety, and others.

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“Wildfire smoke isn’t just a respiratory issue—it affects mental health, too,” said Kari Nadeau, a professor in Harvard’s TH Chan School of Public Health, in a press release. “Our study suggests that—in addition to the trauma a wildfire can induce—smoke itself may play a direct role in worsening mental health conditions like depression, anxiety, and mood disorders.”

The researchers focused on the period in 2020 between July and December in California; that year was the state’s worst wildfire season on record, with more than 4.3 million acres burned. In that period, there were a total of 86,609 mental health visits to hospital emergency departments for things like psychoactive substance use, nonmood psychotic disorders, anxiety, and depression; that’s over a period when the average wildfire-related PM2.5 level was 6.95 micrograms per cubic meter of air — below the EPA-set standard of 9.0 micrograms.

But that level rose to 11.9 micrograms/cubic meter during peak wildfire months, and to a dangerous 24.9 micrograms/cubic meter during a peak period in September 2020. Those increases were then directly linked to an increase in mental health emergency visits — a 10 microgram/cubic meter increase in PM2.5 sent those visits higher, and the increase was statistically significant. Specifically, the highest and statistically significant bumps were for depression, other mood-affective disorders, and anxiety. The increase lasted for up to seven days after exposure to the higher wildfire smoke levels.

Importantly, the increase in mental health impacts was not evenly distributed among the population. The visits increased most among women, children and young adults, Black and Hispanic people, and Medicaid recipients.

“The disparities in impact by race, sex, age, and insurance status suggest that existing health inequities may be worsened by wildfire smoke exposure,” said Youn Soo Jung, the study’s lead author and also of Harvard’s public health school. “We need to make sure everyone has access to mental health care during wildfire seasons, particularly the most vulnerable groups and particularly as wildfires become more frequent and severe as a result of climate change.”

If that piece of the findings sets off any alarm bells, it should. The study was funded by a grant from the National Heart, Lung, and Blood Institute, part of the National Institutes of Health. NIH, along with the rest of the federal government, is in the midst of a seek-and-destroy process to eliminate anything that even vaguely addresses things like healthcare or outcomes disparities, so the fact that wildfire smoke affects women and minorities more may be just the kind of thing that ends up on some “cost-cutting” ghoul’s radar.