Planting trees is not enough, to have results against pollution in cities it is also necessary to plan their variety. A Finnish study conducted by the University of Helsinki with the Finnish Meteorogical Institute reveals how to design city avenues to improve air quality.
The research (Large-eddy simulation of the optimal street-tree layout for pedestrian-level aerosol particle concentrations - A case study from a city-boulevard ", recently published in Atmospheric Environment: X) has examined some streets in the Finnish capital , where it was found that the best result against particulates is obtained in an avenue lined with a row of lime trees flanked by two rows of lower Swedish rowans.
For pedestrians, the air is a fifth cleaner than that obtained with four rows of trees of different heights, the researchers explained.