Aether was commissioned by Berkeley Homes to undertake an air quality assessment for the proposed installation of gas fired boilers at 250 City Road. Dispersion modelling was undertaken and a ‘slightly adverse’ impact on local nitrogen dioxide concentrations was found at worst case locations. Other pollutants were not of concern. One uncertainty in the modelling was the background nitrogen dioxide concentrations, as the data obtained from the nearby background monitoring station differed to that obtained from the Defra background concentration maps. In addition, the current pollution contribution from City Road was also uncertain. Therefore a nitrogen dioxide monitoring survey using diffusion tubes was commissioned to determine the current pollution levels at various points around the development site.
At the time of monitoring, the area was a building site and therefore none of the buildings that will be constructed as part of the development were available for monitoring at. The site also needed to be clear of obstructions. Therefore the diffusion tubes were placed around the perimeter of the development site and from this interpolations had to be made.
Five diffusion tubes were exposed at the extremes of the site for periods of between 4 and 5 months in accordance with the UK Nitrogen dioxide survey timetable. One location was at first floor level to provide an indication of concentrations above ground level.
The results indicated that concentrations exceeded the annual mean nitrogen dioxide objective in some residential locations close to City Road, which confirmed the indications provided by the dispersion modelling. Therefore, the installation of NOx/NO2 filters was recommended at these locations.
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