City Hall has said the controversial expansion of Ultra Low Emission Zone (ULEZ) across the whole of London is ‘working better than expected’ according to new data.

A report covering the first six months of the expansion suggests that pollutant emissions in 2023 with the London-wide ULEZ expansion in place are 'dramatically lower' than compared to a scenario without it.

Within the outer London ULEZ area, nitrogen oxide (NOx) emissions from cars are estimated to be 13% lower and 7% lower from vans than a scenario without the expansion, while PM2.5 exhaust emissions from cars in outer London are estimated to be 22% lower (6% more than expected).

TfL said that across all measures, these impacts are aligned with, and in many cases greater than, what it estimated in its consultation on the expansion.

In the six-month timeframe covered by the report, roadside NO2 concentrations in outer London have dropped by up to 4.4% compared to what would have been expected without the London-wide expansion of the scheme.

The report also shows the impact of the ULEZ as a whole on roadside NO2 concentrations across London.

Levels in outer London are estimated to be 21% lower, levels in central London 53% lower and levels in inner London 24% lower.

TfL said that London’s air quality, including outer London which historically has on average had worse air quality than the rest of England, now has levels of pollution much closer to the rest of the country.

It added that compliance levels also increased further than expected, with 96.2% of all vehicles subject to the ULEZ recorded driving in London now compliant, up from 90.95% in June 2023 and 90,000 fewer non-compliant vehicles detected on an average day in February 2024.