New review highlights air pollution’s effect on children’s brains

A review of 40 peer-reviewed studies  highlights the effect of air pollution on children’s brains. The work was undertaken by a team from the University of California-Davis with the intention of mobilising policy change.

The 40 studies that the team referenced were largely undertaken in the US, Mexico and Europe, with one each from Asia and Australia. 

All the studies included measures of outdoor air pollution and brain outcomes for children at various ages, from newborns up to 18-year-old adults. The majority of these used cohorts in the United States, Mexico and Europe, with one each from Asia and Australia.

Anthony Wexler, a professor at UC Davis and director of its Air Quality Research Center said: ‘A lot of researchers working on brain development, whether it’s autism, Alzheimer’s or something else, really discounted for a long time the environmental factors. They argued that it’s genetic or some other factor other than exposure to air pollution. That’s changed a lot recently because of all this research literature.’

The wide age range of children included in the various research, allowed the team to examine those effect at various points in development. However, as Anna Parenteau, a Ph.D. student in psychology at UC Davis said: ‘A lot of these studies include children in places with air pollutant levels that are well below limits set by U.S. or European regulations.’

Following the study, the team shared their preliminary conclusions:

• Air pollution exposure is associated with a range of structural brain alterations in children, including alterations in cortical thickness and surface area, white matter volume, and subcortical volume.
• Associations between pollution exposure and structural MRI measures are specific to the region examined, the type of pollutant, and the timing of exposure.
• DTI and functional connectivity findings are mixed, and more research is needed.
• Air pollution exposure is associated with alterations in brain metabolites, although no consistent associations with certain metabolites have been detected.
• Large studies have linked air pollution exposure to childhood CNS tumour incidence.
• Autopsy studies indicate structural and vascular damage from air pollution exposure.
• Early development (e.g., prenatal period, early childhood) appears to be a vulnerable window of exposure.
• The pollutants of most concern seem to be PM2.5 and traffic-related pollutants.

The study also includes a series of recommendations which include making it easier for people to get access to air purifiers and to enable communities to measure their own air pollution with low cost sensors.

Camelia Hostinar, an associate professor of psychology said: ‘We’re seeing differences in brain outcomes between children with higher levels of pollution exposure versus lower levels of pollution exposure. We listed air purifiers as one of the policy recommendations, and that is something that could be subsidised or provided in schools and other places where children spend a lot of time. These can be quite effective.’

Sally Hang, a Ph.D. student in psychology and the study’s first co-author also suggest that: ‘Anybody collecting data from human participants on brain outcomes or cardiovascular outcomes or anything else could easily add questions to assess air pollution exposure, such as obtaining their addresses.’

The full report can be read here.