Medical experts claim that children exposed to pollutant fumes in the womb or during the first two years of life are up to twice as likely to develop autism spectrum disorder (ASD).
The study adds to growing research that has found a link between air pollution and ASD.
It found children exposed to increased levels of the pollutant chemicals chromium and styrene increased their risk of developing ASD, which affects one in 68 young people.
Styrene is used in the production of plastics and paints and is a by-product of burning petrol in cars.
Chromium is a heavy metal emitted from power plants and as a result of industrial processes such as the hardening of steel.
Few studies of autism have included environmental exposures while taking into account other personal and behavioural risk factors.
Researchers suggested other pollutants such as cyanide, methylene chloride, methanol and arsenic used in a number of industries, and found in exhaust fumes, may also have an effect.
The study was conducted by Dr Evelyn Talbott, of the University of Pittsburgh graduate school of public health, who said: “ASDs are a major public health problem, and their prevalence has increased dramatically.
“Despite its serious social impact, the causes of autism are poorly understood.
“Very few studies of autism have included environmental exposures while taking into account other personal and behavioural risk factors.
“Our analysis is an addition to the small but growing body of research that considers air toxics as one of the risk factors for ASD.”
The study interviewed 217 families of children with ASD, and examined how many pollutants they had been exposed to during the first two years of life.
Researchers found children exposed to styrene and chromium were at a 1.4 to twofold greater risk of ASD, after accounting for the age of the mother, maternal cigarette smoking, race and education.
A spokesman for the National Autistic Society Scotland said: “The causes of autism are still being investigated and we welcome any research which may further our understanding of the condition.
“Many experts believe that the pattern of behaviour from which autism is diagnosed may not result from a single cause. There is strong evidence to suggest that it can, however, be caused by a variety of physical factors, all of which affect brain development. There is also a strong genetic indicator.
“The research carried out by Dr Talbott and her team focused on a relatively small sample. Far more testing, both in terms of sample numbers and geographical area, is necessary.
“What we do know, however, is that the 58,000 individuals with autism and their families living in Scotland right now can benefit from a range of individually tailored support and advice in order to allow people to live more independently.”
Autism is described as a spectrum condition. This means that while people with autism, including Asperger’s syndrome, share certain characteristics, they will be highly individual in their needs and preferences.
Some people with autism are able to live relatively independent lives but others may face additional challenges, including learning disabilities, which affect them so profoundly that they need support in many areas.