Can Wildfire Smoke During Pregnancy Raise the Risk of Autism? Here’s What New Research Says

Two groundbreaking studies published in early 2026 are drawing attention to a troubling connection: exposure to wildfire smoke during pregnancy may be linked to a higher likelihood of autism in children. While the findings don’t prove that smoke directly causes autism, they add to a growing body of evidence suggesting that air pollution — and wildfire smoke in particular — can have profound effects on fetal brain development.

Here’s what we know so far, and why it matters.

Study #1: The Tulane University Study

The first study, led by researchers at Tulane University and published in the journal Environmental Science & Technology in January 2026, analyzed data from more than 200,000 mother-child pairs in Southern California between 2006 and 2014. Researchers tracked the mothers’ exposure to wildfire smoke — specifically fine particulate matter known as PM 2.5 — at their home addresses during pregnancy, then followed up to see which children received an autism diagnosis by age five.

The results showed a clear pattern tied to the third trimester of pregnancy. Compared to mothers who experienced no smoky days, those exposed to just one to five days of wildfire smoke had roughly an 11% higher likelihood of having a child diagnosed with autism. That figure rose to about 12% for six to ten smoky days, and to 23% for more than ten days of exposure.

The association was strongest among women who didn’t move during their pregnancy, suggesting that sustained, localized exposure — rather than a brief encounter with drifting smoke — may play a more significant role.

Lead author David Luglio, a postdoctoral fellow at Tulane, noted that the number of days of exposure mattered more than the average concentration of smoke over the entire pregnancy. Even a single day of exposure showed a measurable effect.

Study #2: The UC Davis and UCLA Study

A second, even larger study came out around the same time. Conducted by researchers at UC Davis Health and UCLA and published in the journal Environment International, this one examined a massive dataset of over 8.6 million births across California from 2001 to 2019 — making it the largest study to date on wildfire smoke and neurodevelopment.

Its findings were more nuanced. When looking at average smoke exposure across all births, the link to autism was relatively weak. But when researchers zeroed in on the most intense smoke events — specifically, days where particulate levels were in the top 10% — the association became much stronger.

The results were particularly striking in areas with normally clean air. Among mothers in the highest percentile of wildfire smoke exposure who lived in regions with relatively low background pollution (like rural or suburban areas far from highways and industry), the likelihood of having a child diagnosed with autism was a full 50% higher.

Senior author Rebecca J. Schmidt, a professor at the UC Davis MIND Institute, pointed out that these extreme smoke events are becoming more common as climate change drives larger, more frequent wildfires.

Important Caveats

Both studies come with significant limitations, and the researchers are careful to emphasize that their findings do not establish a direct causal link between wildfire smoke and autism.

Autism is widely understood to be a complex condition influenced by a combination of genetic and environmental factors. These studies identify wildfire smoke as one potential environmental contributor — a piece of a much larger puzzle.

David Mandell, a psychiatry professor at the University of Pennsylvania who was not involved in either study, noted that the dose-response pattern wasn’t perfectly consistent. In some cases, the highest exposure groups didn’t show the expected increase in risk, which he said warrants caution in interpretation and further replication.

There are also practical limitations: the studies estimated smoke exposure based on outdoor air at home addresses, but couldn’t account for time spent indoors, air filtration, mask use, or other protective behaviors.

Why It Matters

Despite these caveats, the research is significant for a few reasons.

First, wildfire seasons are getting worse. In the western United States, large wildfires now burn for an average of 52 days, up from just six days in the 1970s and 1980s, according to the USDA. The devastating fires that swept through Los Angeles County in early 2025 are a vivid reminder that smoke exposure is no longer a rare event for millions of Americans.

Second, wildfire smoke is uniquely harmful. Research suggests it is roughly ten times more toxic than exhaust from burning fossil fuels. The ultra-fine particles released by burning vegetation and structures penetrate deep into the lungs and can enter the bloodstream, potentially crossing the placental barrier.

Third, these findings align with a broader body of research connecting prenatal air pollution exposure — including from traffic, industrial emissions, and heavy metals — with increased autism risk. A 2021 Harvard study similarly found that late-pregnancy exposure to air pollution was associated with poorer neurodevelopmental outcomes.

What Can Be Done?

The researchers behind both studies emphasize that wildfire smoke is a “potentially modifiable” risk factor — meaning that protective measures could make a real difference. For pregnant individuals living in fire-prone areas, practical steps include monitoring air quality, staying indoors on smoky days, using HEPA air purifiers, and wearing well-fitted masks (such as N95s) when outdoor exposure is unavoidable.

On a broader scale, the findings underscore the need for stronger climate and wildfire mitigation policies, as well as public health strategies that prioritize the safety of pregnant people during smoke events.

As Tulane’s Mostafijur Rahman put it: as wildfires grow more frequent and intense, understanding their relationship with developmental outcomes is critical to building effective protections for the most vulnerable.

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Sources:

• Luglio, D. et al. “Prenatal Exposure to Wildfire and Autism in Children.” Environmental Science & Technology, January 2026. (Link)
• O’Sharkey, K. et al. “Exposure to intense wildfire smoke during pregnancy may be linked to increased likelihood of autism.” Environment International, February 2026. (Link)
• Mogensen, J.F. “California wildfire smoke linked to increased autism diagnoses, new study finds.” Scientific American, January 21, 2026. (Link)
• Teirstein, Z. “Growing evidence points to link between autism and wildfire smoke.” Grist, February 12, 2026. (Link)
• Sharp, M.R. “Exposure to intense wildfire smoke during pregnancy may be linked to increased likelihood of autism.” UC Davis Health News, February 12, 2026. (Link)