Children who were exposed to high levels of air pollution during their first year of life or whose mothers lived in environments with high levels of air pollution during pregnancy have a greater risk of developing autism, according to a recent study conducted by USC and Children’s Hospital Los Angeles scientists.

The study, “Traffic Related Air Pollution, Particulate Matter, and Autism,” suggests that exposure to traffic-related air pollution during pregnancy and the first year of life leads to a two-fold risk of autism. The study was published Monday online in the Archive of General Psychiatry and focused on the research done by a team composed of Keck, CHLA and UC Davis MIND Institute investigators.

“This work has broad potential public health implications,” said Heather Volk, the study’s principal investigator and  an assistant professor of preventative medicine at USC, in a release. “We’ve known for a long time that air pollution is bad for our lungs, and especially for children. We’re now beginning to understand how air pollution may affect the brain.”

Researchers examined the amount of near-roadway traffic pollution and measures of regional air quality, building on previous research by Volk and colleagues.

“We took into account how far away people lived from roads, meteorology such as which way the wind was blowing, how busy the road was, and other factors to study traffic-related pollution,” she said in a release. “We also examined data from air quality monitors, which measure pollution over a larger region that could come from traffic, industry, rail yards or many other sources.”

The study, funded in part by a grant from the National Institute of Environmental Health Sciences, monitored children’s development and examined where families lived during each trimester of pregnancy and at the baby’s birth with relation to the proximity to major road or freeways.

This is the first study to affiliate exposure to vehicular pollutants with risks of autism. Other studies have examined the influence of air pollution during pregnancy and have concluded that it has physical and developmental effects on the fetus as well examining the effects of air pollution exposure in the first months of life, which has been connected to delay in cognitive development.

The Center for Disease Control and Prevention reported a 57 percent increase in autism between 2002 and 2006. Historically, genetic factors have been considered the cause of autism, but recently there has been an increased awareness that increase in the developmental disorder could be because of other factors.

Volk and colleagues are now studying the relationship between genes related to autism and environmental exposures to identify any factors that could make people genetically more vulnerable to particular pollutants.