A new US study suggests exposure to traffic-related air pollution during pregnancy and infancy may be linked to an increased risk of autism.
Researchers from the University of Southern California monitored the relationship between air quality and autism in 500 children.
Head of Developmental Disorders research at the Telethon Institute, Dr Andrew Whitehouse says this is just the first step when it comes to looking for environmental factors related to autism.
"This is a well conducted study that has great potential to advance our understanding of the biological pathways that lead to autism," says Dr Andrew Whitehouse.
"There is an increasing recognition amongst researchers that certain aspects of our environment may interact with our genetic make-up to cause autism.
The hunt is on for these environmental risk factors, and this study suggests that traffic-related pollution may be one of the many pieces of this puzzle".
However, Dr Whitehouse urges parents not to be prematurely concerned.
"This study represents the first step in our marathon of understanding environment contributions to autism," he says.
"Traffic pollution may be one of the likely 'many' environmental factors that may contribute to autism - but the reality is that we just don't know for certain yet.
This research is a good first step, but without completing the marathon, there is absolutely no reason for parents to be concerned".