Basagana X, Esnaola M, Rivas I, Amato F, Alvarez-Pedrerol M, Forns J, Lopez-Vicente M, Pujol J, Nieuwenhuijsen M, Querol X, Sunyer J. Neurodevelopmental deceleration by urban fine particles from different emission sources: a longitudinal observational study. Environ Health Perspect. 2016 Oct;124(10):1630-6.

BACKGROUND: A few studies have reported associations between traffic-related air pollution exposure at schools and cognitive development. The role of PM components or sources other than traffic on cognitive development has been little explored.

OBJECTIVES: We aimed to explore the role of PM sources in school air on cognitive development.

METHODS: A cohort of 2618 schoolchildren (average age 8.5 years) belonging to 39 schools in Barcelona (Spain) was followed up for a year. Children completed computerized tests assessing working memory, superior working memory and inattentiveness during four visits. Particulate matter less than 2.5 micrometre (PM2.5) was measured during two one-week campaigns in each school outdoors and in the classroom. Source apportionment resulted in nine sources: mineral, organic/textile/chalk, traffic, secondary sulphate & organics, secondary nitrate, road dust, metallurgy, sea spray, and heavy oil combustion. Differences in cognitive growth trajectories were assessed with mixed models with age-by-source interaction terms.

RESULTS: An interquartile change increase in indoor traffic-related PM2.5 was associated with reductions in cognitive growth equivalent to 22% (95% confidence interval (CI): 2%, 42%) of the annual change in working memory, 30% (95% CI: 6%, 54%) of the annual change in superior working memory, and 11% (95% CI: 0%, 22%) of the annual change in the inattentiveness scale. None of the other PM2.5 sources was associated with adverse effects on cognitive development.

Traffic was the only source of fine particles associated with a reduction in cognitive development. Reducing air pollution from traffic at primary schools may result in beneficial effects on cognition.

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