Mayor hails huge success of landmark ULEZ and bold clean air policies as deaths linked to toxic air fall by around 40 per cent

 

• New independent analysis by experts from Imperial College London shows that, between 2019 and 2024, the estimated deaths associated with air pollution in London have reduced by around 40 per cent. (1)
• This new data reflects the impact of the Mayor’s bold, sustained action to tackle air pollution in the capital, including the introduction of the world’s largest clear air zone of its kind - the Ultra Low Emission Zone (ULEZ)
• New figures out today show estimated reductions of 28 per cent in PM2.5 and 41 per cent in NO2 London-wide, which are associated with direct improvements in Londoner’s health (2)

 

The Mayor of London, Sadiq Khan, has hailed the success of London’s bold policies to reduce air pollution and improve health across the capital, as new independent data reveals that there has been an approximate 40 per cent reduction in the number of estimated deaths linked to air pollution between 2019 and 2024. (1) 

New analysis by Imperial College London’s Environmental Research Group, commissioned via Imperial Projects, has also found that toxic air pollution in London has reduced markedly since 2019, translating into a substantial fall in the overall health burden: 

1. Nitrogen Dioxide (NO2) levels, a traffic-related gaseous pollutant that exacerbates asthma, impedes lung development, and raises the risk of lung cancer, are down 41 per cent (2)
2. Fine particulate pollution (PM2.5) level, extremely small particles that can result in serious health impacts especially in vulnerable groups of people such as the young, elderly, and those with respiratory problems, are down 28 per cent (2) 

In April 2019, the Mayor of London launched the world’s first 24-hour Ultra Low Emission Zone (ULEZ) in central London. The zone was expanded across inner London in 2021, and finally to cover the whole capital in August 2023, bringing the air quality and associated health benefits to more then 9 million people living in London. The ULEZ is now the largest clean air zone in the world of its kind. 

Earlier estimates for 2019 suggested around 4,000 premature deaths were attributable to air pollution, based on evidence available at the time. This new Imperial College study uses an updated and more advanced methodology, drawing on a much larger body of scientific evidence, which shows that the impact of long-term exposure to air pollution on health is even greater than previously understood. 

To provide a fair comparison, the updated methodology has been applied to both 2019 and 2024. This estimation shows a reduction from around 6,400-8,000 premature deaths in 2019 to approximately 3,800-5,100 in 2024 – a fall of around 40 per cent. (1) 

According to the research by Imperial’s independent experts, the boroughs with the highest number of deaths attributable to air pollution per 100k residents in 2024 were in outer London boroughs like Bexley, Havering and Sutton. The expansion to outer London was met with significant opposition. This underlines the significance of the Mayor taking on his opponents, while also reflecting the age profile of these boroughs, and the vulnerability of older people to diseases linked to air pollution. 

Earlier this month a study by Imperial College London also found the Toxicity Charge and central London ULEZ are associated with a fall in hospital admissions in London – revealing that since their introduction, the schemes were linked to 9.3 per cent reductions in annual trends for heart-related emergency admissions, and a 5.1 per cent drop in annual trends in hospital admissions for all illnesses and health conditions in the scheme area. (3) 

New evidence shows stronger associations between air pollution exposure and premature deaths, and recent evidence continues to show associations with dementia, type 2 diabetes, and childhood asthma. This underlines that the health impacts of air pollution in 2019 were even more severe than previously understood. reinforcing why taking action was so important. 

Despite this progress, long term exposure to air pollution is still estimated to contribute to 3,800-5,100 premature deaths across London in 2024. The economic cost of this mortality burden in 2024 is estimated at £3.8 billion to £5.1 billion. (4) 

The improvement in London’s air quality reflects the cumulative impact of the Mayor’s bold action to cut emissions, alongside long-term pollution trends. In 2024, London met legal limits for NO2 pollution for the first time in 2024 – almost 200 years earlier than experts predicted if no action was taken.(5) 

The Mayor of London, Sadiq Khan, said: “The evidence is now overwhelming and unarguable: the bold action we have taken in London has reduced pollution, improved public health and saved lives. From childhood asthma to dementia, we know that a wide range of illnesses are linked to air pollution. This latest data shows why expanding ULEZ London-wide was even more important than we previously thought and is transforming lives right across our capital.  

“It’s great to be back at the Aldgate School, which I first visited after being elected as Mayor in 2016 to meet children who were trying to protect their playground from air pollution. Back then, I was told that under London’s current policies, it would take almost 200 years to bring the air within legal limits. We’ve done it in nine. 

“The decision to expand the ULEZ was not an easy decision, but it’s now proven beyond doubt that it was crucial to protect the health and lives of Londoners. However, I’m not complacent. Despite our incredible progress, there is still more to do.” 

Since taking office in 2016, the Mayor has: 

1. Introduced the Ultra Low Emission Zone, the world’s largest clean air zone of its kind, which has led to an estimated 27 per cent reduction of harmful roadside NO2 concentrations across London (6,7) with over 97 per cent of vehicles seen driving on London’s roads meeting ULEZ emissions standards. (7)
2. Supported the transition to lower emission vehicles, with more than 53,000 older, more polluting vehicles removed from London’s roads thanks to the scrappage scheme. (8)
3. Protected the most vulnerable by investing £2.7m to provide indoor air quality filters for classrooms in 200 primary schools, so more children can breathe clean air. 
4. Increased the number of zero emission buses in TfL’s fleet from just 30 in 2016 to over 3,000 zero emission buses as of June 2026, one of the largest fleets in Europe.
5. Provided £33 million through the Mayor’s Air Quality Fund which has supported more than 100 projects across London. 

The Mayor announced the findings during a visit to the Aldgate School, which he first visited after being elected in 2016. Then, concentrations in the playground breached legal limits for nitrogen dioxide. There has been a 48 per cent reduction in nitrogen dioxide concentrations at the school between 2016 and 2025. (9). The school also has an indoor air quality filter, and preliminary monitoring is showing promising results in the filtered classrooms. 

ULEZ expansion has not impacted footfall or retail and leisure spending in either outer London or London as a whole. Visitor footfall in outer London increased by almost 2 per cent in the year after the London-wide ULEZ expansion.(7)

Dr Sarah Elkin, Consultant in Respiratory Medicine Imperial College Healthcare NHS Trust and Co- Clinical Director London Respiratory Clinical Network said: “London’s air is getting cleaner and it’s saving lives – as a respiratory consultant looking after Londoners who struggle with these conditions every day, I know just how important it is that we continue to push forward with the incredible progress we’ve already made. I am delighted to see the findings of today’s report which show that London’s bold actions to improve air quality have led to cleaner air – which we know is vital for Londoners’ health and wellbeing. The new evidence also underlines the strong links between exposure to air pollution and poor health, so it's fantastic to see this new research showing the estimated reduction in early deaths.”

Karen Bonner, Chief Nurse for the NHS in London, said: “These findings are a reminder of what is at stake when we talk about air quality. Thousands of Londoners are now living longer, healthier lives because the air they breathe is cleaner. Children with asthma, elderly residents, and those with respiratory conditions are among those who benefit most. There is still more to do, but this data shows that sustained, evidence-led action to tackle air pollution saves lives and we are committed to continuing to work alongside the Mayor and our partners to protect the health of every Londoner.” 

Antha Williams, who leads the Environment Program at Bloomberg Philanthropies, said: “London’s historic progress shows what’s possible when leaders take bold action to tackle air pollution and put public health first. Bloomberg Philanthropies has partnered with London on its clean air efforts, and the city's results demonstrate how strong, data-driven policies can reduce harmful pollution, improve health outcomes, and save lives. As communities everywhere confront the impacts of air pollution, London’s success is a powerful example of what can be achieved through sustained leadership and action. The lessons from London are helping cities around the world advance clean air solutions through Breathe Cities.”"    

Jemima Hartshorn, Founder and Director at Mums for Lungs said: “This research shows that big schemes like the ULEZ really help clean up the air. And cleaner air means healthier Londoners. Thank you Sadiq, for your leadership!  But every year thousands of Londoners die from air pollution. Over a hundred thousand children went to hospital with breathing issues in London in 2024. And other cities and regions are still more polluted than London now – it could not be clearer: Londoners need more action, and so does the rest of the country!” 

Rosamund Adoo-Kissi-Debrah CBE, WHO BreatheLife Ambassador and Founder of the Ella Roberta Family Foundation said: "The figures released today prove what I have known for a long time, that air pollution is killing people.  We may not be able to see it, but the toxic air we are breathing every day is causing irreparable damage to every person who lives in London. The first steps of cleaning up the air in London with ULEZ have clearly been worth it to save people’s lives, literally saving thousands of people’s lives - a 40 per cent reduction in lives lost.  The pressure air pollution is placing on the NHS is huge and measures taken in London are working. But there is still so much more to do to improve air quality in line with the World Health Organisation (WHO) guidelines, not just in London but for the rest of the UK too.  I urge the Government to do more, to go further and reduce toxic NO2 in particular, found in diesel cars, vans and freight, which is still four times above the legal limit set by WHO.  And the highest contributor of PM2.5 in London, woodburning - there is no place for it when we know the damage it is doing to people’s health. The UK, one of the most developed nations in the world has 500 people dying prematurely each week from air pollution. With temperatures rising, today is one of the highest air pollution days and we are all at risk from this invisible, yet preventable threat. We need to tackle it to reduce the burden on the NHS, to save the economy billions and stop people from dying prematurely."

Professor Sir Stephen Holgate CBE, special adviser on air quality at Royal College of Physicians said: “The scale of improvement in this new analysis is so encouraging. A fall of 40 per cent in estimated pollution-related deaths is a powerful reminder that decisive, sustained action - such as the expansion of the Ultra Low Emission Zone in London - can deliver real, measurable benefits for people's health.

“But further action is needed to protect the health of Londoners. The priority must now be to build on this progress and ensure that every community, in every part of London, can benefit from clean and healthy air."   

"Cecilia Vaca Jones, Executive Director, Breathe Cities said: “Congratulations to Mayor Khan and to every Londoner who has breathed cleaner air because of this work. London’s journey is an inspiration and it is leadership like this that drives us at Breathe Cities. We see every day how the right policies, backed by data and community voices, can bring about change. London shows what is possible and we are taking those lessons around the world so that more babies, more children, more families, more communities can breathe cleaner air.”      

Dr David Dajnak from the Environmental Research Group (ERG), Imperial College London, said: “Our study highlights two key findings: London’s air quality has improved markedly since 2019, but despite this progress, air pollution remains a serious public health risk.” 

Dr Dimitris Evangelopoulos, also from ERG, said: “New scientific evidence reinforces what we already know: in 2024, air pollution remains associated with thousands of premature deaths across the capital, highlighting the need for sustained efforts to reduce pollution further in every part of London.”

Christina Calderato, Director of Strategy at TfL, said: “This research is fantastic news and, while we cannot rest on our laurels, we know that preventing even one death associated with air pollution creates an enormous impact for the family and friends of the loved one. To know that so many more deaths have likely been avoided demonstrates the importance and success of taking bold and ambitious action, such as the expansion of the ULEZ. Alongside our efforts to decarbonise the public transport network, we are striving to create a London that is healthier, greener and cleaner for everyone both now and in the future.”     

Jane Burston, CEO, Clean Air Fund said: "A 40 per cent reduction in deaths linked to air pollution in just five years is a remarkable public health achievement. This research adds to a growing body of evidence that clean air measures, like London’s ULEZ, save lives. This progress represents ongoing efforts from city leaders, civil society organisations, and communities who have pushed for ambitious action.

“With air pollution still well above guideline levels from the World Health Organization, the priority now must be to build on this momentum so that every Londoner can feel the health benefits of cleaner air." 

Ben Pearce, Head of the Health Effects of Air Pollution programme at Impact on Urban Health, said: "We warmly welcome this progress. The fact that fewer people are dying due to air pollution shows what's possible when government acts decisively. But the job isn’t done. 

“Air pollution has never hit Londoners equally. It falls hardest on children, on people with existing health conditions, on people from racialised communities, and on people from lower income areas. 

“Cleaner air for London is vital, but the real test is whether the children and communities most exposed are seeing the biggest gains. That's where the next phase of action has to focus."

Izzy Romilly, Sustainable Transport Manager at Possible said: "These new findings go to show what's possible with leadership - ambitious action can change and save lives. But our air is still toxic and the job isn't over. 

“We need politicians of all parties and levels of government to work together and set out a vision for a UK where no one breathes toxic air, wherever they live or work.

“We know what needs to happen: we need a national Clean Air Act, ramped-up action on transport and diesel, quality housing with clean, cheap energy for all, and no more airport expansion. With vision and action we can continue working towards WHO guidelines and make sure no one is made sick by the air they breathe."

Love Ssega, Founder, LIVE + BREATHE, said: ""Clean air isn't a luxury; it's the baseline for any city that says it cares about its people. These figures show what becomes possible when ambition is backed by action and when we choose long-term wellbeing over short-term convenience. 

Because every cut in pollution isn't just a number on a chart, it's kids breathing easier on their way to school. It's communities with less weight on their lungs and more space to grow. And it's more people, especially those hit hardest, shaping the future of this city through culture, creativity, and leadership that already exists in every neighbourhood.

“At LIVE + BREATHE, we believe creativity has a vital role to play in driving environmental and social progress. The progress London has made demonstrates that ambitious policies can deliver real benefits for people's everyday lives, while reminding us that there is still more work to do to ensure every Londoner can breathe clean air, regardless of where they live.”