title: Neurodevelopmental Deceleration by Urban Fine Particles from Different Emission Sources: A Longitudinal Observational Study.
abstract: 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.
  
  
  OBJECTIVE
  We aimed to explore the role of PM sources in school air on cognitive development.
  
  
  METHODS
  A cohort of 2,618 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 ≤ 2.5 μm (PM2.5) was measured during two 1-week campaigns in each school, both outdoors and in the classroom. Source apportionment resulted in nine sources: mineral, organic/textile/chalk, traffic, secondary sulfate and 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 range increase in indoor traffic-related PM2.5 was associated with reductions in cognitive growth equivalent to 22% (95% 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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  Basagaña X, Esnaola M, Rivas I, Amato F, Alvarez-Pedrerol M, Forns J, López-Vicente M, Pujol J, Nieuwenhuijsen M, Querol X, Sunyer J. 2016. Neurodevelopmental deceleration by urban fine particles from different emission sources: a longitudinal observational study. Environ Health Perspect 124:1630-1636; http://dx.doi.org/10.1289/EHP209.
authors.affiliation: Centre for Research in Environmental Epidemiology (CREAL), Barcelona, Catalonia, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Basagaña
authors.forename: Mikel
authors.initials: M
authors.lastname: Esnaola
authors.forename: Ioar
authors.initials: I
authors.lastname: Rivas
authors.forename: Fulvio
authors.initials: F
authors.lastname: Amato
authors.forename: Mar
authors.initials: M
authors.lastname: Alvarez-Pedrerol
authors.forename: Joan
authors.initials: J
authors.lastname: Forns
authors.forename: Mònica
authors.initials: M
authors.lastname: López-Vicente
authors.forename: Jesús
authors.initials: J
authors.lastname: Pujol
authors.forename: Mark
authors.initials: M
authors.lastname: Nieuwenhuijsen
authors.forename: Xavier
authors.initials: X
authors.lastname: Querol
authors.forename: Jordi
authors.initials: J
authors.lastname: Sunyer