Wandsworth Council have released a report by King’s ERG, which evaluates the impact of Transport for London’s bus retrofit programme on nitrogen dioxide (NO2) concentrations along Putney High Street.

This study’s primary aim was to assess the impact on ambient NO2 concentrations of Transport for London’s retrofitting of exhaust emission control units to a large proportion of the buses passing along Putney High Street. These Selective Catalytic Reduction (SCR) units were specially adapted for urban driving conditions, with the aim of reducing NOX and NO2 gases in the exhaust.

The study made use of high resolution continuous NO2 monitors at the kerb and façade, coupled with Automatic Number Plate Recognition Cameras, to relate individual vehicle emissions to pollution concentrations. It identified a clear decrease in nitrogen dioxide concentrations co-incidental with the timing of the introduction of retrofitted buses and independent of confounding factors, such as the weather. The overall measured decrease was around 20%, however, due to the nature of the reduction, a more substantial decrease was seen in peak hourly mean concentrations.

Despite the improvement, nitrogen dioxide levels still regularly breach the EU hourly target and more action is needed to bring them down.

Councillor Jonathan Cook, Wandsworth Council's spokesman for the environment, said: "The Putney High Street project provides a new blueprint for how we measure air quality around heavy traffic and analyse the success of new investment in cleaner vehicles. There is no longer any need to rely on manufacturers’ claims or projections - impacts can now be measured in real world conditions where we all live and breathe."

Wandsworth Council’s press release can be seen here

Please click on the link below to download the full report.

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Item date 16/07/2014