The way in which London's trees can improve air quality by filtering out pollution particulates, which are damaging to human health has been revealed by scientists at the University of Southampton.
Their study indicates that the urban trees of the Greater London Authority (GLA) area are removing somewhere between 850 and 2000 tonnes of particulate pollution (PM10) from the air every year.
An important development in the research, carried out by Dr Matthew Tallis, is that the methodology allows the prediction of how much pollution will be removed in the future as the climate and pollution emissions change.
This shows the real benefits of the planned increase in the number of street trees in London and throughout England, including the GLA's plan to increase the area of urban trees by 2050 and the current government's 'Big tree plant' initiative.
The research found that the targeting of tree planting in the most polluted areas of the GLA area and particularly the use of a mixture of trees, including evergreens such as pines and evergreen oak, would have the greatest benefit to future air quality in terms of PM10 removal.
"Trees have evolved to remove CO2 from the atmosphere, so it's not surprising that they are also good at removing pollutants. Trees which have leaves the whole year are exposed to more pollution and so they take up more. Using a number of different tree species and modelling approaches, the effectiveness of the tree canopy for clean air can be optimized," said a co-author Professor Gail Taylor.
The study is published this month in the journal Landscape and Urban Planning.