Scientists model impact of green infrastructure on city centre traffic pollution

Trees and grass not only make town centres look greener, they make urban spaces healthier by reducing harmful particulates in the air.

Scientists from EarthSense Systems and the University of Leicester published the results of a study into the effect of urban trees on air pollution. The results show a direct link between air pollution and green infrastructure, with trees and grass cover contributing to a reduction in concentrations of fine particulate matter (PM2.5).

The research shows that the aerodynamic dispersive effect of trees results in a 9% reduction in PM2.5 concentrations. A decrease of PM2.5, by 2.8% owing to deposition on trees and 0.6% owing to deposition on grass, was also observed.

“This is the first time a study of this scale and nature has been conducted in the UK,” said Professor Roland Leigh, technical director of EarthSense and director of enterprise at the University of Leicester’s Institute for Space and Earth Observation. “The results provide valuable information on the interaction of particulate matter and vegetation in the complex urban environment. There are implications on our future modelling of pollutant concentrations, and the structure and positioning of key green infrastructure.” 

Conducted on a larger scale than previous studies, the project utilised the geographic data from aerial mapping company Bluesky, including aerial photography, laser mapped LiDAR and the unique National Tree Map. The University of Leicester led study used modelling techniques such as Computational Fluid Dynamics (CFD), already validated for wind flow and particle dispersion modelling.

EarthSense is a joint venture between Bluesky and the University of Leicester, established to provide commercial access to a range of air quality technologies and research.

James Eddy, managing director of EarthSense Systems and technical director at Bluesky, said: “This study shows the part that green infrastructure can play in reducing the effects of harmful traffic emissions in our city centres. When co-ordinated with an understanding of local implementation and traffic planning, this will be significant in shaping future cities.”

Antoine Jeanjean, lead author of the paper and modeller at EarthSense Systems, said: “The use of the most up-to-date and accurate geographical data, combined with proven modelling techniques on this scale, is a first, and we hope it will inform and influence further studies and real world projects.”

The paper, titled Modelling the effectiveness of urban trees and grass on PM2.5 reduction via dispersion and deposition at a city scale by Antoine Jeanjean, non-executive director Paul Monks and Professor Roland Leigh, has been published in peer reviewed format prior to full publication in the Atmospheric Environment Journal and is freely available by clicking here