THE CAPTURE OF PARTICULATE POLLUTION BY TREES AT FIVE CONTRASTING URBAN SITES

Abstract

The beneficial effect of trees on urban air quality through their uptake of particulates has been widely discussed in the literature and is often cited as one of the multiple benefits of amenity planting. However, uptake rates have not been measured for European amenity trees and thus only limited advice can be given on the design of urban planting to maximise removal of particulates. Data from the network of urban air quality monitoring sites suggests that today particulates may represent a greater threat to human health in urban areas than any other air pollutant. Clear understanding of both the value of urban trees in removal of particulates and the principle factors which determine capture efficiency are therefore required. The work presented here shows that significant quantities of particulate matter may be removed from the atmosphere by trees of various age and size at a variety of urban locations throughout the UK. The rate of uptake of these particles was shown to vary between species, with trees that display a more aerodynamically rough surface performing as the best air pollution filters. Interestingly, it appears that younger, smaller trees of the same species are also highly effective at removing pollutant particles due to their greater foliage densities compared to much larger mature specimens.