Software to help towns and cities use street-planting to reduce citizens’ exposure to air pollution has been developed by researchers at the University of Birmingham.
Street planting, or ‘green infrastructure’, is an essential part of the urban realm, but there is a misconception that plants remove or ‘soak up’ a lot of pollution.
Instead, planting at this scale primarily serves to redistribute pollution by changing air currents within streets and beside open roads.
This means the layout and orientation of a street, as well as the position and amount of planting within that street, are critical to its impacts on local air quality.
The software – the Green Infrastructure for Roadside Air Quality or ‘GI4RAQ’ Platform – has been designed by experts in the University of Birmingham’s Institute of Forest Research (BIFoR) and School of Geography, Earth and Environmental Sciences, in partnership with practitioner organisations including Transport for London, Greater London Authority and Birmingham City Council.
It is the result of three years’ collaboration, funded mainly through three Innovation grants from the Natural Environment Research Council.
‘In reducing our exposure to pollution from nearby vehicles, strategic planting can complement essential emission reductions in reducing health impacts. But it’s not as simple as thinking that any planting will do good – if indiscriminate, it’s just as likely to have a negative impact.
‘There are many good reasons to invest in green infrastructure but, if planting in the name of improving air quality, we must ensure it delivers genuine benefits. By estimating the benefits at planning, we can ensure good schemes are robust to cost-cutting and fully realised.’
DR JAMES LEVINE
Free to use and open-source, the software enables practitioners to estimate the changes in pollutant concentrations (throughout the cross-section of a street) resulting from different planting schemes.
It focuses on key pollutants from road transport: NO2 (nitrogen dioxide) and PM2.5 (fine particulate matter).
Its calculations draw on wind data from monitoring stations across the UK, and determine how background wind conditions interact with the local urban form and planting specified by the user.
The software’s performance and underlying science are documented in a paper published last month in Forests, an open-access journal.
Informed by their work with Dr Levine, Transport for London is currently exploring a potential ‘healthy and resilient streets’ scheme with the Greater London Authority.
Dr Levine is also in discussion with The Mersey Forest and Liverpool City Council regarding a scheme in central Liverpool.
‘The GI4RAQ Platform bridges the gap between academic researchers and organisations like The Mersey Forest, cutting through the often-mixed messages regarding the impacts of vegetation on urban air quality, in support of projects delivering genuine, lasting benefits.’
PAUL NOLAN OBE
Director of the Mersey Forest