Expanded Ultra Low Emission Zone Six Month Report

On 8 April 2019 the Mayor of London launched the world’s first 24-hour Ultra Low Emission Zone (ULEZ) in central London. On 25 October 2021 the zone was expanded up to, but not including, the North and South Circular Roads. The ULEZ is now 18 times the size of the original area and covers 4 million people – over a third of London’s population.

The ULEZ does not operate in isolation. It operates in conjunction with the London-wide Low Emission Zone (LEZ). This was originally launched in 2008. It is the oldest of the capital’s emission control schemes and applies to large and heavy vehicles. In March 2021 enforcement of tougher emission standards for the LEZ began. Prior to this, the standards hadn’t changed since 2012. The LEZ standards are now the same as the ULEZ standards for most large and heavy vehicles.

Six months on from the ULEZ expansion and over a year on from the enforcement of tighter LEZ standards the data indicate that these schemes are having a significant impact on the number of older, more polluting vehicles seen driving in London and the levels of harmful pollution Londoners are exposed to.

• A bigger share of vehicles in London are cleaner. Six months after the launch of the ULEZ expansion nearly 94 per cent of vehicles seen driving in the whole zone meet the strict ULEZ standards on an average day, up from 87 per cent in the weeks before the zone expanded and up from 39 per cent in 2017 when impacts associated with the ULEZ began. The compliance rate on boundary roads is 90 per cent and the compliance rate in outer London is 85 per cent.
• There are fewer older, more polluting vehicles in the zone. There were 67,000 fewer non-compliant vehicles in the zone on an average day compared with the period right before the ULEZ expanded, down from an average of 124,000 daily vehicles. This is a reduction of 54 per cent.
• The Low Emission Zone continues to have an impact. Large and heavy vehicles, which fall under the London-wide LEZ, have a compliance rate of 96 per cent, up from an estimated 48 per cent in February 2017.
• There has been an overall reduction in vehicles and traffic flows in the zone. Overall, there were 21,000 fewer vehicles seen in the zone on an average day (a reduction of 2 per cent) and early estimates suggest traffic flows are around 2 per cent lower than the weeks before the expansion launched. However, many factors are currently affecting traffic trends in London and we will continue to review the data to better understand the impact of ULEZ expansion in the longer term.
• Drivers are ditching diesel cars. On average there were 44,000 fewer diesel cars driving in the zone each day – a 20 per cent decrease since the weeks before the ULEZ expanded.
• This means people in the zone are breathing cleaner air. The amount of pollution in the air, the concentration, is what ultimately impacts people’s health. Harmful NO2 concentrations alongside roads in inner London are estimated to be 20 per cent lower than they would have been without the ULEZ and its expansion. In central London, NO2 concentrations are estimated to be 44 per cent lower than they would have been. This decrease in concentrations close to roads would have also led to reduced air pollution in locations away from traffic.
• The air is also cleaner on the boundary. All monitoring sites on the boundary of the expanded zone have seen reductions in NO2 concentrations, with an estimated 17-24 per cent reduction in pollution on the boundary compared to a scenario without the ULEZ.