Net impact of London Strand-Aldwych pedestrianisation project on air quality and noise

Abstract

Pedestrianisation in urban areas has the potential to reduce air and noise pollution but may lead to increased pollution in surrounding streets. To date, there are very few long-term monitoring studies that assess the net impacts of pedestrianisation on air quality and noise. This study uses a dense low-cost particulate matter and environmental noise monitoring network to assess the net impacts of the Strand-Aldwych pedestrianisation project (SAPP) in central London on particulate matter and noise pollution. Monitoring started before traffic was excluded from the Strand in June 2021 and continued through re-development works in 2022 and post-works in 2023. Collected particulate matter data was complemented with data from the Automatic Urban and Rural Network and London Air Quality Network sites. Results show a statistically significant decrease in NOx and environmental noise pollution on the Strand between summer 2021 and summer 2023. PM2.5 levels have also decreased at street level on the Strand but have increased on Aldwych and other surrounding streets relative to concurrent background levels measured at roof level. PM2.5 is mostly driven by larger scale background inputs in central London and meteorological conditions while NOx and environmental noise are more directly related to local sources at street level. The latter are therefore stronger indicators of improved air quality and reduced noise after pedestrianisation.