Exposure to air pollution on route to school can decrease working memory growth, study reveals

A study conducted by the Barcelona Institute for Global Health (ISGlobal) has revealed that air pollution exposure on home-to-school routes can have harmful effects on cognitive development in children. The aim of the study was to evaluate the impact of air pollution exposure during the home-to-school walking commute.

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The study determined the link between decreased working memory and exposure to black carbon and fine particulate matter (PM2.5) during the home-to-school walking commute. The study was performed in the BREATHE project. Earlier research in the project discovered that traffic-related pollutants exposure in schools was related to reduced cognitive development. The conclusions of a previous study had revealed that 20% of a child's everyday dosage of black carbon - a pollutant directly associated with traffic - is inhaled during urban commutes.

Mar Álvarez-Pedrerol, ISGlobal researcher and lead author of the study stated that the conclusions of earlier experimental and toxicological studies have revealed that these short exposures to very high pollutant concentrations can have an excessively high impact on health. She further added that the harmful impacts may be more significant in children due to their higher respiratory rate and smaller lung capacity.

The study, involving over 1,200 children between 7 and 10 years old, was conducted in Barcelona. All of the participants walked to school from home every day.  The children’s attention capacity and working memory was evaluated many times during the one year study. Their air pollution exposure over the same duration was measured based on the projected levels of the shortest walking route from home to their school.

Statistical analysis of the results indicated that exposure to black carbon and PM2.5 was associated with a decrease in the working memory growth: an interquartile range increase in black carbon and PM 2.5 levels were related with a drop of 3.9% and 4.6%, respectively, in estimated annual working memory growth. No noteworthy associations were found with NO2 exposure and none of the pollutants examined were observed to have any impact on attention capacity. In this study, boys were much more sensitive than girls to the impacts of both black carbon and PM2.5.

Jordi Sunyer, head of ISGlobal's Child Health Programme and co-author of the study stated:

Above all, we do not want to create the impression that walking to school is bad for children's health because the opposite is true: walking or cycling to school, which builds physical activity into the child's daily routine, has health benefits that far outweigh any negative impact of air pollution."

According to Álvarez-Pedrerol, reduction in private vehicle use for the school run will create safer and less polluted home-to-school routes.