Exposure to outdoor air pollution may increase the risk of intellectual disability in children, a study conducted in the UK has found. The study, published in the Journal of Intellectual Disability Research, found that British children with intellectual disabilities were more likely than their peers to live in areas with high outdoor air pollution. "We know that people with intellectual disabilities in the UK have poorer health and die earlier than they should," said Eric Emerson from the University of Sydney in Australia. "This research adds another piece to the jigsaw of understanding why that is the case and what needs to be done about it," Emerson said. The findings come from an analysis of data extracted from the UK's Millennium Cohort Study, a nationally representative sample of over 18,000 children born between 2000 and 2002. Averaging across ages, children with intellectual disabilities were 33 per cent more likely to live in areas with high levels of diesel particulate matter, and 30 per cent more likely to live in areas with high levels of nitrogen dioxide. They were 30 per cent more likely to live in areas with high levels of carbon monoxide, and 17 per cent more likely to live in areas with high levels of sulphur dioxide. The researchers, including those from the Lancaster University in the UK, note that intellectual disability is more common among children living in more socio-economically deprived areas, which tend to have higher levels of air pollution. However, exposure to outdoor air pollution may impede cognitive development, thereby increasing the risk of intellectual disability.