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The Press Association: Filter-like trees improve city air

Filter-like trees improve city air
(UKPA) – 3 days ago
Trees in London improve air quality by filtering out pollution particulates
which cause problems like asthma.

New research found that the urban trees of the Greater London Authority
(GLA) area remove somewhere between 850 and 2,000 tonnes of particulate
pollution (PM10), which can be inhaled by humans, from the air every year.

The University of Southampton 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

One of the paper’s authors, Professor Gail Taylor, said: “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

The study also looked at predictions of particulate volumes in future
climate and for five tree planting scenarios in London.

Using seasonal rather than hourly data was shown to have little impact on
modelled annual deposition of pollution (PM10) to urban canopies, suggesting
that pollution uptake can be estimated in other cities and for the future
where hourly data are not available.

Co-author Peter Freer-Smith, chief scientist for Forest Research (Forestry
Commission), said: “We know that particulates can damage human health, for
example exacerbating asthma, and this reduction in exposure could have real
benefits in some places, such as around the edge of school playgrounds.

“Urban green space and trees give a wide range of benefits and this study
confirms that improving air quality is one of them and will also help us to
get the most out of this benefit in future.”

The findings were published this month in the journal Landscape And Urban

Copyright C 2011 The Press Association. All rights reserved.

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