New research in the journal Atmospheric Environment has argued that hedges are often better than trees at soaking up air pollution among tall buildings.
The paper says that whilst tall trees are good at absorbing pollution in more open areas, hedges can trap toxins at exhaust pipe level, reducing people's direct exposure to harmful pollutants. While the authors encourage the planting of trees to clean the air, they recommend that hedges are considered in city planning, given that, in some circumstances, tall trees can trap pollution at street level.
Professor Prashant Kumar maintain that the best way of planting will depend upon local conditions, but suggest that if pavements are wide enough, councils should try to plant low hedges between pedestrians and the street.
Talking to BBC News, Kumar said: “The big thing about hedges is that they are right down at tailpipe level. The emissions from vehicles starts to dilute very quickly as you move away from the road - so any hedge that acts as a barrier slowing down the airflow and catching pollutants on the leaves is going to offer people in homes better protection."
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