While it is believed that genetics plays a strong role in the development of autism spectrum disorder (ASD), in utero environmental exposures have also been linked to ASD risk. New research in the journal Environmental Health Perspectives analyzed data from a nested case-control study of participants in the Nurses’ Health Study II to explore maternal exposure to particulate matter (PM) air pollution and odds of ASD risk in offspring. 

Based on the residential locations of the study participants, monthly ambient exposure predictions of airborne particulate matter with an aerodynamic diameter ≤1µm (PM10) and ≤2.µm (PM2.5) were generated. ASD cases were more likely to be male, to have been exposed to maternal preeclampsia or maternal smoking during gestation, and to be missing data on premature birth compared withcontrols. Ambient PM2.5 concentrations during pregnancy were significantly associated with having a child diagnosed with ASD, with the strongest association seen with PM2.5 exposure during the third trimester. Exposure before or after pregnancy had weaker associations with ASD and PM10-2.5 during pregnancy had little association with ASD.

Further investigation into the biological mechanism that may underlie the association between PM exposure during pregnancy and ASD incidence in offspring could help to determine if air pollution is indeed a modifiable risk factor for autism; if so, pollution-reduction initiatives could be enacted to help lower the incidence of ASD.