Figures from the London Assembly detailing vehicle use within the expanded Ultra Low Emission Zone in London shows that there was a 37% drop in the number of non-compliant vehicles during the first month of operation.

On 25 October 2021, the Mayor of London expanded the ULEZ up to, but not including, the North and South Circular roads. The new zone is 18 times larger than before with nearly four million people living in the zone, which measures 147 square miles (380 square kilometres), covering a quarter of London’s area.

The compliance rate, which is the percentage of vehicles detected in the zone that meet the emission standards, during the first month was 92%, compared to the compliance levels in 2017 of 39% and up from 87% in the two weeks before the scheme was launched. This means on an average weekday, there were 47,000 fewer non-compliant vehicles detected in the expanded zone compared to the two weeks before the scheme was
introduced.

The London Assembly says on an average weekday there were 11,000 fewer vehicles driving each day in the zone. This is a 1% reduction, although it warns it will take more time for traffic patterns post launch to fully emerge.