Exposure to air pollution on the way to school can have damaging effects on growth of children’s working memory, suggests new research published in the journal Environmental Pollution. It found an association between a reduction in working memory and exposure to fine particulate matter (PM2.5) —fine inhalable particles that have diameters of 2.5 micrometres or less — and black carbon — a pollutant directly related to traffic — during the walking commute to and from school. The findings of an earlier study had shown that 20 per cent of a child’s daily dose of black carbon is inhaled during urban commutes. Exposure to PM2.5 and black carbon was associated with a reduction in the growth of working memory.