air quality (microclimate)

In hot sunny weather trees improve air quality largely by lowering temperature. The cooling effect of trees depends on the reflectance of the foliage, density of shade and rate of transpiration, which in turn depend largely on growing conditions. Trees also affect the concentration of air pollutants near ground level through their effect on air movement

This definition is abridged from A – Z of tree terms: A companion to British arboriculture.
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