Children who are exposed to air pollution on the walk between home and school are at greater risk of cognitive damage, according to a new Spanish study led by the Barcelona Institute for Global Health (ISGlobal).
The research, published in the journal Environmental Pollution, finds that children who are exposed to fine particulate matter (PM2.5) and black carbon during the walking commute to and from school are more likely to have a reduction in working memory.
Previous research conducted by the same team found that exposure to traffic-related pollutants in school itself was associated with slower cognitive development. The goal of the new study was to investigate the impact of exposure to air pollution during the walking commute to school. The findings of an earlier study had shown that 20 percent of a child’s daily dose of black carbon — a pollutant directly related to traffic — is inhaled during urban commutes.
“The results of earlier toxicological and experimental studies have shown that these short exposures to very high concentrations of pollutants can have a disproportionately high impact on health,” said Dr. Mar Álvarez-Pedrerol, ISGlobal researcher and first author of the study.
“The detrimental effects may be particularly marked in children because of their smaller lung capacity and higher respiratory rate,” she adds.
The study, which was conducted in Barcelona, involved over 1,200 children (ages seven to 10) from 39 schools, all of whom walked to school on a daily basis. The children’s working memory and attention capacities were assessed several times during the 12-month study. Their exposure to air pollution during this period was based on estimated levels of the shortest walking route to their school.
Statistical analysis shows that exposure to PM2.5 and black carbon was associated with a reduction in the growth of working memory. No significant effects were found after exposure to NO2 and none of the pollutants studied were observed to have any effect on attention capacity. However, boys were much more sensitive than girls to the effects of both PM2.5 and black carbon.
“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,” said Dr. Jordi Sunyer, head of ISGlobal’s Child Health Programme and co-author of the study.
“The fact that children who walk to school may be more exposed to pollution does not mean that children who commute by car or on public transport are not also exposed to high levels.”
Álvarez-Pedrerol said the solution is essentially the same for everyone: “Reduce the use of private vehicles for the school run and create less polluted and safer home-to-school routes.”