Exposure to aircraft noise may lead to impaired cognitive performance in schoolchildren, but the evidence for road traffic noise is still limited. We studied the association between long-term exposure to road traffic noise and schoolchildren’s cognitive development.We followed-up a population-based sample of 2715 children aged 7-10 years from 39 socioeconomically paired schools in Barcelona (Catalonia, Spain). Children underwent computerized cognitive tests 4 times during one year to assess growth (n = 10112). We assessed working memory (2-back task, detectability), superior working memory (3-back task, detectability), and inattentiveness (Attention Network Task, hit reaction time standard error). Traffic-related noise and air pollution were measured indoors and outdoors at schools, at the start of the school year and 9 months later. Noise was measured with a type II sound level meter using standard protocols to obtain long-term A-weighted average levels (LAeq, in dB). We obtained indoor noise levels in all classrooms by correcting for classroom orientation and change between years. Linear mixed effects models were adjusted for age, sex, maternal education, socioeconomic status, and traffic-related air pollution.Exposure to road traffic noise outdoors at schools was consistently associated with smaller working memory (2-back and 3-back) and greater inattentiveness growth in children. E.g., an interquartile range increase in noise was related to -7.51 points (95%CI: -11.1; -3.91) in 3-back detectability. Exposure to road traffic noise in classrooms was only associated with inattentiveness. Associations were robust to all adjustment sets.Children exposed to greater outdoor levels of road traffic noise at schools exhibited slower cognitive development. Exposure to road traffic noise in classrooms, where noise levels are lower, was associated only with inattentiveness, which might suggest that inattentiveness is a more noise sensitive outcome than working memory.
