Central London ULEZ - Six Month Report

This report evaluates the impact of the central London Ultra Low Emission Zone (ULEZ) in its first six months of operation.

For the first time, this report contains evaluation of the impact on air pollution concentrations and emissions.



Between February 2017 and September 2019, there has been a 32 micrograms per cubic metre reduction in roadside concentrations of nitrogen dioxide in the central zone, a reduction of 36 per cent. Trend analysis shows that, for the period July to September 2019, NO₂ concentrations at roadside locations in central London were on average 24 ug m^-3 lower, equating to a reduction of 29 per cent, compared to a scenario where there was no ULEZ.



In September 2019 the average compliance rate with the ULEZ standards was around 77 per cent in a 24 hour period (and 74 per cent in congestion charging hours). This is much higher than 39 per cent in February 2017 and the 61 per cent in March 2019 (congestion charging hours).