Hedges are better than tall trees in reducing the impact of air pollution and cities could protect their residents by strategically planting low hedges along roads in built-up environments, new research has found.
The study, led by the University of Surrey's Professor Prashant Kumar and published in the journal Atmospheric Environment, recommended that 'green infrastructure' be integrated into urban planning.
"We all know air pollution is a major factor of everyday urban life," says Professor Kumar. "This comprehensive review highlights that trees and hedges, as well as other green infrastructure, must be used strategically to help create healthier, less polluted cities that are also more pleasant for everyone to live and work in."
'Thick, dense and tall vegetation barriers' are best for protecting people from vehicle emissions in open road conditions, while green walls and roofs, as well as low hedges, are the best option for built-up areas of tall buildings. Around skyscrapers, high-level greenery like trees 'generally have a negative impact on air quality', the study found.