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In this one year report, we evaluate the impacts of the ULEZ and the LEZ schemes, focusing on one year following the ULEZ expansion to inner London and for the LEZ, over a year and a half on from the enforcement of tighter LEZ standards.


Air pollutant concentrations

  • The air in the zone is substantially cleaner. The ULEZ expansion has led to four million people breathing cleaner air, including 1,362 more schools. Harmful nitrogen dioxide (NO2) concentrations are estimated to be 21 per cent lower than they would have been in inner London without the ULEZ and 46 per cent lower than they would have been in central London. This is above what was predicted for the scheme. Substantial reductions in NO2 concentrations were seen at roadside locations, with a 56 per cent reduction in central London, 47 per cent in inner London, and 37 per cent in outer London since 2017. Background monitoring sites away from the main road network also had significant reductions in NO2 of 47 per cent in central and 45 per cent in inner London, since 2017. Unlike central and inner London sites, average concentrations at outer London background sites have remained constant since 2021.
  • The boundary roads have also benefited from cleaner air. All air quality monitoring sites on the boundary roads recorded large reductions in NO2 concentrations and there has been an estimated reduction of 19-27 per cent compared to a scenario without the ULEZ with the impact increasing over time. Showing therefore there has been no displacement of pollution to the boundary.
  • NO2 levels have not returned to those experienced pre-pandemic, indicating that even as traffic levels have risen; cleaner vehicles in the fleet caused by the ULEZ and its expansion, have had sustained and positive impacts on air pollution meaning concentrations continue to be far below what they would have been otherwise.
  • Particulate matter (PM2.5) levels have also continued to reduce across London with a 41 per cent reduction in average concentrations in central and inner London since 2017.

Read the full report https://www.london.gov.uk/prog...

NO2 impacts of ULEZ
NO2 impacts of ULEZ