Study links pollution from traffic to autism

Exposure to traffic pollution while in the womb is linked to a small but significant increased risk of autism in children, a major study has found.

Scientists in Canada looked at rates of autism in a population of 132,256 children born between 2004 and 2009 in the Vancouver area.

At age five, 1% of the children were diagnosed with autism spectrum disorders (ASDs).

Children whose mothers were exposed to higher levels of nitric oxide (NO) air pollution while pregnant were more at risk of developmental condition that affect the ability to interact socially or communicate.

Although the increase was just 0.07% per tiny step rise in NO levels, it was statistically significant after accounting for other factors that may have influenced the outcome.

NO is one of a range of air pollutants emitted from the exhausts of road vehicles.

In the body, natural levels of the gas are important to nerve function, regulating blood pressure and the immune system.

But excess NO is associated with harmful effects in adults including metabolic disorders, low blood pressure and lung conditions.

The study did not find a significant link between rates of autism and two other traffic pollutants, microscopic particles known as PM2.5s, and nitrogen dioxide.

The scientists concluded: “These findings suggest that reducing exposure to NO for pregnant women may be associated with a reduction in ASD incidence.”