Kerb-side trees could reduce the level of particulate matter (PM) inside homes by as much as 60%, according to a study by Lancaster University.

PM poses a significant threat to health. Exposure can damage the heart, the lungs and the brain and lead to a reduction in life-expectancy. A large proportion of indoor PM comes from road traffic.

Illustration of experiment results.

In an experiment carried out in 2013 a row of young silver birch trees was temporarily installed outside four terraced houses and PM levels were measured inside these houses before, during and after installation. The results were compared with four adjoining houses where no trees were installed. By the end of the two-week experiment the houses where the trees were installed showed a decrease in indoor PM levels of up to 64%. The houses outside the tree line showed no significant change over the same period.

Robert St. Are these trees actively capturing pollution from the 3,000+ vehicles that use this road each day?

Examination of tree leaves after the experiment showed that they were capturing PM produced by the traffic rather than just providing a screen. The selection of tree species is important in maximising this effect. The trees need to be managed to prevent them from producing dense crowns as this could create a canyon effect which stops pollution from being dispersed by the wind.

To access the original research click HERE