A team at the University of Cambridge explored whether adding green spaces around schools and playgrounds can act as a natural shield against air pollution from traffic. The study, published in Science of The Total Environment, looks at practical, city scale strategies to create healthier learning environments and cleaner play areas through plant barriers instead of relying solely on mechanical filtration or distant policy shifts.
Children who go to schools near busy roads face higher exposure to polluted air because their developing airways react more to irritants and they breathe faster during active play and classroom activity than adults. The researchers point out that this increased exposure happens during crucial growth years when long term health patterns can be shaped by air pollutants. The study therefore focuses on real world settings where classrooms meet asphalt and asks how urban design choices can influence the air that students actually inhale during the school day.
To test the idea, investigators compared pollution levels along a six lane traffic corridor with measurements taken in a schoolyard behind a fence at a distance of about 30 meters from the highway. They discovered that a carefully chosen mix of trees and shrubs could substantially reduce the outdoor fine particle concentration in the air that children breathe. Specifically, the plant barrier cut PM10 particles by roughly 78 percent compared with the roadside atmosphere, and PM2.5 particles, the smaller and more dangerous fraction, were reduced by about 80 percent in the protected zone. These reductions translate into meaningful exposure differences during outdoor recess, sports, and everyday school activities.
The researchers also identified Western red cedar, a conifer known as Thuja plicata, as a particularly effective component of the barrier for trapping airborne particles. The findings suggest that this evergreen species, with its slender, dense foliage and year round leaf surface, can act as a more efficient filter than many other landscaping choices when placed between a busy road and a play area. Co author Professor Barbara Maher noted that the tree’s numerous fine leaves intercept dust and extend the time particulates spend in the air before settling, contributing to cleaner air where children spend their day.
In broader terms, the team emphasizes that green barriers can complement broader city wide air quality improvements. Thoughtful landscape design offers immediate, local benefits by reducing students exposure to traffic emissions while urban planners pursue longer term strategies to cut overall pollution. The results align with a growing body of evidence showing vegetation can help mitigate street level air pollution, especially when plant choice height and spacing are tailored to the specific site conditions.
Overall, the Cambridge study argues for integrating green infrastructure into school settings as a protective measure that improves outdoor air quality without requiring people to change their behavior first. It highlights opportunities for cooperation among school administrations, city planners, and landscape professionals to create healthier spaces for learning and play, even as climate conditions influence air quality on a regional scale. [Citation: University of Cambridge study on green barriers in school environments].