London’s Ultra-Low Emission Zone Expansion Has Effectively Reduced Air Pollution, Report Finds

In London, the implementation and expansion of the Ultra-Low Emission Zone (ULEZ) has reduced air pollution by decreasing amounts of nitrogen dioxide, fine particulate matter and carbon emissions, according to new data by City Hall reviewed by independent air quality experts.

In total, air quality in London is improving at a faster rate compared to the rest of England, and the ULEZ has reduced enough carbon emissions to equal the impact of removing 3 million one-way passenger trips from Heathrow Airport to New York City, according to the report.

The Ultra-Low Emission Zone was first implemented in 2019, when it became the first low-emission zone to operate 24/7. In February 2023, a peer-reviewed study by the London mayor’s office showed that the zone was working after an initial expansion to include inner London. At that point, the zone had led to a 21% decrease in nitrogen dioxide levels in inner London and a 46% reduction in these emissions in central London. That report also found a decline in fine particulate matter and carbon emissions both inside the ULEZ and across London entirely.

In August 2023, the ULEZ was expanded again to cover the entire city, with expectations that this move would improve air quality for 5 million more people living in London’s outer boroughs. The ULEZ is now the largest low-emission zone globally.

Now, new data proves the expanded low-emission zone has made serious improvements to the air quality in and around the city, including a 27% decline in nitrogen dioxide levels, across London.

“When I was first elected, evidence showed it would take 193 years to bring London’s air pollution within legal limits if the current efforts continued. However, due to our transformative policies we are now close to achieving it this year,” London Mayor Sadiq Khan said in a statement. “Today’s report shows that ULEZ works, driving down levels of pollution, taking old polluting cars off our roads and bringing cleaner air to millions more Londoners.”

The report revealed that fine particulate matter levels were 31% lower in the outer boroughs of London than they would have been without the expansion, and air quality has improved at 99% of city-wide air quality monitoring sites since 2019.

According to data from Transport for London (TfL), the number of ULEZ-compliant vehicles in London is now 96.7%, compared to just 39% in February 2017 and 91.6% in June 2023. There are about 100,000 fewer non-compliant vehicles per day on average in London as of September 2024 compared to June 2023, just before the ULEZ was expanded to cover the entire city. 

Officials noted the transition to cleaner vehicles is in part thanks to the ULEZ scrappage program, which offered a total of £200 million ($258.37 million) in grants for people who wanted to either retrofit non-compliant vehicles, scrap them with goals of buying a cleaner vehicle, or donate the older vehicles to Ukraine. The program received over 54,000 applications.

For critics concerned over economic impacts of the ULEZ on local tourism and businesses, officials noted that retail and leisure spending weren’t impacted by the expansion, and visitor footfall even increased nearly 2% since the zone was expanded to cover the outer boroughs.

To further improve London’s air quality, the city is also adding more “zero-emission” buses, offering free and discounted public transportation opportunities, expanding cycling networks and installing more EV charging infrastructure. The mayor has set a target for at least 80% of trips in the city to be made by walking, cycling or riding public transportation by 2041.

“Improving air quality through initiatives like the Ultra Low Emission Zone in London is crucial for protecting public health and reducing the burden of disease,” Dr. Maria Neira, director of the Department of Environment, Climate Change and Health at the World Health Organization (WHO), said in a statement. “Cleaner air leads to healthier communities, lower rates of respiratory and cardiovascular illnesses, and a better quality of life for all residents.”