Exposure to air pollution during pregnancy and first of year of life may have links to autism in children, a U.S.-based study has found.

The study, conducted in California and published online Monday in Archives of General Psychiatry, examined the relationship between traffic-related air pollution, air quality, and autism. It found children living in homes with highest levels of traffic-related air pollution were three times as likely to have the developmental disorder when compared with children residing near lowest levels of exposure.

Recently, environmental factors such as air pollution have been identified as a potential risk factor for autism, a spectrum disorder characterized by communication and social interaction problems.

The population-based study examined data obtained from participants enrolled in the Childhood Autism Risks From Genetics and the Environment study, which included 279 children with autism and 245 with typical development. The children in the study were predominantly male, and most were non-Hispanic white, or Hispanic.

To estimate exposure for each trimester of pregnancy and first year of life, the study looked at a mother’s address from birth certificate and addresses reported in a residential history questionnaire. Air pollution was gauged both locally and regionally using a line-source air-quality dispersion model, as well as with data from the Environmental Protection Agency’s Air Quality System.

In particular, the study looked at atmospheric particulate matter (PM) and nitrogen dioxide levels in geographical areas.

The study noted the need for additional research on the effects of exposure to pollutants and other biological susceptibility factors related to autism.

“Although additional research to replicate these findings is needed, the public health implications of these findings are large because air pollution exposure is common and may have lasting neurological effects.”