Living near a busy road could double the risk of childhood autism, scientists warn.
A new study found exposure to air pollution in the womb or during the first year of life was linked to a dramatic increase in a child's chances of having the disorder.
Children from homes with the highest traffic pollution levels were three times more at risk than those from the least exposed homes, the 'Daily Mail' reported.
Experts described the finding as "important" but stressed it did not prove that traffic pollutants could affect brain development.
Scientists in California set out to investigate a possible link between traffic pollution and autism rates, saying they were on the increase.
They looked at data on 279 children affected by autism compared to 245 children without autism matched for age and background.