The ULEZ in London has led to four million people breathing cleaner air

In 2019 the Mayor of London launched the world’s first 24-hour Ultra Low Emission Zone (ULEZ) in central London. Later in 2021, the zone was expanded across inner London, 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 four million people (44 percent of London’s population). The ULEZ in London has led to four million people breathing cleaner air.

The ULEZ does not operate in isolation. It operates in conjunction with the London-wide Low Emission Zone (LEZ), 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. Before 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.   

In a new report, the city evaluates 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. The findings indicate that the Mayor’s air quality policies, and in particular the ULEZ and LEZ schemes, are having a significant impact in reducing the number of older, more polluting vehicles seen driving in London and reducing the levels of harmful air pollution that Londoners are exposed to. In summary, the key findings are:  

Traffic and vehicle compliance
  • The vehicles traveling in London are increasingly cleaner. The overall ULEZ compliance rates have continued to increase, with 94.4 percent of vehicles seen driving in the zone on an average day, meeting the ULEZ standards a year following the expansion. This increased from just 39 percent when the expansion was announced in 2017.
  • The number of older, more polluting vehicles in the zone has decreased significantly. An almost 60 percent reduction in non-compliant vehicles detected in the zone since the expansion came into operation, an average reduction of 74,000 polluting vehicles per day. 
  • The heavy vehicle fleet is cleaner because of the London LEZ. The strengthening of emission standards resulted in a significant increase in compliance rates, such that compliance reached 97 percent, which increased from 90 percent in February 2021, immediately before the tightening of the standards. 
  • The proportion of diesel cars on London’s roads has reduced. In October 2022, the proportion of kilometers driven in London by diesel cars was estimated to have reduced from 32 percent to about 25 percent in inner London, showing the impact of the expansion in reducing diesel cars driving in inner London. In terms of private hire vehicles (PHVs), petrol hybrid electric vehicles comprise the largest proportion of this fleet. PHVs experienced an increase in the proportion of electric vehicles from October 2021, when the ULEZ was expanded in central and inner London. Changes to the composition of PHVs have been highly influenced by the additional licensing requirements for newly registered PHVs set by Transport for London to reduce emissions from these vehicles. 
  • There has been an overall reduction in vehicles, and traffic flows in the zone. In October 2022, there were 47,000 fewer vehicles seen in the zone on an average day (a reduction of almost 5 percent), and data suggest traffic flows are around three percent lower than in the weeks before the expansion. This is similar to the reduction in traffic flows observed following the introduction of the central London ULEZ. The COVID-19 pandemic also affected traffic levels. However, in outer London, traffic levels have largely returned to pre-pandemic levels, but in central and inner London, they remain below what they were in 2019.   

Cleaner air

  • Pollution emissions have been reduced dramatically. Cumulatively since 2019, it is estimated the ULEZ led to nitrogen oxide (NOx) emissions from road traffic reducing by 13,500 tonnes across London over the four years compared with what they would have been without the ULEZ, a reduction of 23 percent. Within the ULEZ area, NOx emissions are estimated to have reduced by 5,000 tonnes, a reduction of 26 percent, over the same period. Reductions in NOx emissions were seen across all vehicle types, but the greatest proportion occurred in TfL busses at 70 percent. Cumulatively, emissions of fine particulate matter (PM2.5) are estimated to have reduced by 180 tonnes across London since 2019, compared to without the ULEZ, a reduction of 7 percent. Within the ULEZ area, PM2.5 emissions are estimated to have reduced by 80 tonnes, a reduction of 19 percent, over the same period. 
  • Carbon emissions from vehicles have also been reduced. Cumulatively since 2019, it is estimated that the ULEZ has led to a reduction of around 800,000 tonnes of CO2 emissions from vehicles across London over the four years compared to without the ULEZ, a three percent saving. Within the ULEZ area, this is a saving of 290,000 tonnes, a reduction of 4 percent over the same period. 

Source: City of London

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