New studies link wildfire smoke exposure during pregnancy to higher autism risk in children

Two major studies have uncovered compelling evidence connecting wildfire smoke exposure during pregnancy to increased autism diagnoses in children, adding to growing concerns about the health impacts of worsening wildfire seasons.

The first study, published in Environmental Science and Technology, tracked over 200,000 children born in Southern California between 2006 and 2014. Researchers found that mothers exposed to wildfire smoke for 10 or more days during their third trimester had a 23% higher risk of having a child diagnosed with autism by age 5. Even shorter exposures of 6-10 days increased the risk by 12%. Importantly, it wasn’t the average smoke concentration that mattered, but the number of exposure days – even a single day had measurable effects.

A second, larger study in Environment International analyzed 8.5 million California births from 2001 to 2019, focusing on intense smoke episodes. Women in the highest exposure category who lived in areas with otherwise clean air showed 50% higher odds of having a child with autism compared to those with lower wildfire smoke exposure.

These findings don’t prove wildfire smoke directly causes autism – researchers emphasize that autism spectrum disorder, which affects one in 31 eight-year-olds in the U.S., likely results from multiple genetic and environmental factors working together. However, the studies add important evidence to our understanding of how environmental pollutants may influence brain development. As wildfires become more frequent and severe due to climate change, understanding these connections becomes increasingly crucial for protecting maternal and child health.