JAMA Netw Open

Prenatal exposure to air pollution may increase autism risk in children

October 28, 2025

Study details: This large, population-based retrospective cohort study in Ontario, Canada (2002–2022) examined associations between prenatal and early-life exposure to fine particulate matter (PM_2.5) components, nitrogen dioxide (NO₂), and ozone (O₃) with childhood autism spectrum disorder (ASD) diagnoses. The study used distributed lag nonlinear models to identify sensitive exposure windows and considered the influence of sociodemographic factors.

Results: Prenatal exposure to specific PM_2.5 components—including elemental carbon, black carbon, organic matter, sulfate, and nitrate—was associated with increased ASD risk, with timing being critical. Stronger associations were observed for elemental carbon, black carbon, and organic matter during the first two trimesters (≈12–18% higher risk per interquartile range increase), and for sulfate during the third trimester (≈15% higher risk). Early postnatal ozone exposure was also associated with a modest increase in risk (≈9%). Sociodemographic factors further modified these associations.

Clinical impact: These findings underscore the importance of considering both the chemical composition and timing of PM_2.5 exposure in assessing autism risk. The results may inform targeted regulatory policies, environmental risk assessments, and early-life interventions to reduce ASD risk associated with air pollution exposure.

Source:

Cloutier M, et al. (2025, October 1). JAMA Netw Open. Prenatal Exposure to Fine Particulate Matter Components and Autism Risk in Childhood. https://pubmed.ncbi.nlm.nih.gov/41129149/