A new study led by the Barcelona Institute for
Global Health, an institute supported by the ”la
Caixa” Banking Foundation, has demonstrated that
exposure to air pollution on the way to school can
have damaging effects on children’s cognitive
The study found an association between a reduction
in working memory and exposure to fine particulate
matter (PM 2.5) and black carbon during the walking
commute to and from school.
The study was carried out in the framework of the
Previous research in the same project found that
exposure to traffic-related pollutants in schools
was associated with slower cognitive development.
The aim of the team undertaking the new study was to
assess the impact of exposure to air pollution
during the walking commute to school.
The findings of an earlier study had shown that 20%
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”
explains 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 was carried out in Barcelona and enrolled
over 1,200 children aged 7 to 10, from 39 schools,
all of whom walked to school on a daily basis.
The children’s working memory and attention capacity
was assessed several times during the 12-month
Their exposure to air pollution over the same period
was calculated on the basis of estimated levels on
the shortest walking route to their school.
Statistical analysis of the findings revealed that
exposure to PM2.5 and black carbon was associated
with a reduction in the growth of working memory: an
interquartile range increase in PM 2.5 and black
carbon levels was associated with a decline of 4.6%
and 3.9%, respectively, in expected annual growth of
No significant associations were found with exposure
to NO2 and none of the pollutants studied were
observed to have any effect on attention capacity.
In this study, boys were much more sensitive than
girls to the effects of both PM2. 5 and black
“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”
explains 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.
His colleague Mar Álvarez-Pedrerol goes on to
explain “The solution is the same for everyone:
reduce the use of private vehicles for the school
run and create less polluted and safer
This is the first time that a team of scientists has
studied the potential impact on cognitive
development of exposure to air pollution in children
who walk to school.
For more information
Impact of commuting exposure to traffic-related air
pollution on cognitive development in children
walking to school.
Alvarez-Pedrerol M, Rivas I, López-Vicente M, et al.
Environ Pollut. 2017 Aug 31;231(Pt 1):837-844.
BRain dEvelopment and Air polluTion ultrafine
particles in scHool childrEn