Traffic was only fine particle source associated with slower cognitive development in children

A study published in Environmental Health Perspectives and led by researchers at the Centre for Research in Environmental Epidemiology (CREAL), an allied ISGlobal centre, has explored associations between cognitive development and the different sources of particulate matter (PM) found in the air in and around schools.

Several studies have reported associations between cognitive development and exposure to traffic-related air pollution in schools. However, according to Xavier Basagaña, a CREAL researcher and the first author of this study, “very little research has focused on the role played in cognitive development by specific PM components or sources other than traffic”.

The CREAL researchers found traffic to be the only source of fine particles associated with slower cognitive development. “This means that reducing traffic-related air pollution in primary schools could have beneficial effects on cognition”, explains Jordi Sunyer, co-director at CREAL and study coordinator.

A cohort of 2,618 schoolchildren, with an average age of 8.5 years, attending 39 schools in Barcelona (Spain) was followed up for one year. In the course of four visits during the year, the children were evaluated using computerized tests to assess working memory (the system that holds multiple pieces of transitory information in the mind where they can be manipulated), superior working memory (the working memory that involves continuous updating of the working memory buffer) and inattentiveness. The presence (outdoors and in the classroom) of fine particulate matter, that is particles that are 2.5 micrometers or less in diameter (PM2.5), was measured in each school during two one-week periods.

Analysis of the results revealed an association between a 4 microg/m3 increase in indoor traffic-related PM2.5 and reductions in cognitive growth equivalent to 22% of the annual change in working memory, 30% of the annual change in superior working memory, and 11% of the annual change in the inattentiveness scale. “No other source of PM2.5 was associated with adverse effects on cognitive development”, adds Basagaña.

Reference

Basagaña X, Esnaola M, Rivas I, Amato F, Alvarez-Pedrerol M, Forns J, López-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 Apr 29;124(5). [Epub ahead of print]