London meets legal limits for toxic NO2 pollution for the first time – almost 200 years earlier than predicted – following the Mayor’s world leading air pollution policies 

• Leading experts at King’s College London estimated that, from when the Mayor came into office in 2016, without additional action it would take 193 years for London to meet legal limits. But under Sadiq’s bold leadership it has remarkably been achieved in just nine years.   

• New independent Government data reveals that London’s air pollution levels fell to within the legal limits for nitrogen dioxide (NO₂) for the first time in 2024.  

• London is leading by example when it comes to air quality, with many other major cities with far smaller populations and fewer vehicles – including Manchester, Liverpool and Birmingham – still exceeding the legal limits.  

The Mayor of London, Sadiq Khan, today hailed the success of his bold air quality policies which have led to the capital’s air pollution levels falling to within the legal limit for the first time.   

In 2019, leading experts at Kings College London estimated that without additional action it would take 193 years for London to meet legal limits, but Sadiq has achieved this aim in just nine years – 184 years early.   

New air quality data from Defra (Department for Environment, Food and Rural Affairs), published today, reveals that London met the Air Quality Standards regulations for the first time in 2024 (1). This is assessed through modelling and Defra’s approved air quality monitoring networks (2). 

Sadiq has achieved this important milestone almost 200 years ahead of predictions, demonstrating the transformative impact of his bold policies to improve London’s air quality and protect Londoners’ health and the environment. Since he took office in 2016, following the implementation of his ambitious policies, such as ULEZ (Ultra Low Emission Zone), levels of toxic NO₂ at roadsides has nearly halved (3). 

In London, around 4,000 premature deaths per year were previously attributed to toxic air (4) and a recent report from the Royal College of Physicians estimates that air pollution costs the UK more than £27 billion per year (5). Air pollution increases the risk of developing asthma, lung cancer, heart disease and stroke, and there is growing evidence that air pollution exposure increases the risk of developing dementia (6). Reaching this milestone of achieving legal limits, years ahead of where we would have been without action, shows that bold policy can produce important benefits. 

Despite huge pressure from many different quarters, from politicians to vested interests, the Mayor pressed on with expanding the ULEZ to all of London and it's proven to be even more effective at cutting air pollution than previously predicted.     

London is leading by example when it comes to air quality, with other major cities  including Manchester, Liverpool and Birmingham - with smaller populations and fewer vehicles - still exceeding the legal limits. The Mayor has delivered a comprehensive package of measures to reduce emissions from all sources in London and is committed to meet the World Health Organization (WHO)’s latest guidelines for NO₂ and PM_2.5 as soon as possible.  

Sadiq’s delivery of the world’s largest clean air zone, the ULEZ, has led to a massive jump of vehicles seen driving in London being ULEZ compliant from 39 per cent  when first introduced to 97 per cent (7). In June this year, the Mayor announced that London has more than 2,000 zero-emission buses on the capital's streets, helping to improve the city's air quality and reduce its carbon emissions. This means two in every nine of London's world-famous red buses have now gone green, which is more than 20 per cent of the entire bus fleet, increasing from 30 in 2016. The Mayor and TfL are working towards his ambitious goal of making all of TfL buses zero emission by 2030.  

The Mayor will continue tackling the sources of air pollution, building on his record breaking achievements over the last 9 years. This includes electrifying all of London’s bus fleet, expanding London’s Electric Vehicle charging network and tackling emissions from the construction industry through the Non Road Mobile Machinery Low Emission Zone. He will also continue delivering his award-winning Breathe London project, providing air quality monitoring in key locations around the capital, enabling Londoners to view real-time, hyperlocal air quality data and take action to tackle air pollution – particularly to help vulnerable groups, including schoolchildren.     

The Mayor of London, Sadiq Khan, said: “This is incredible news. I'm thrilled that London has achieved this historic milestone of meeting the legal limits for nitrogen dioxide for the first time. I remember being told that it would take 193 years to reach legal limits. I decided that this was unacceptable and thanks to the bold policies we put in place, we've managed to do it in just nine years – 184 years early. This means that almost 10 million people are now breathing cleaner air, fewer children are growing up with stunted lungs and fewer people will have to suffer from asthma, dementia and heart disease, which means big savings for the NHS.   

"It wasn't always easy. When we first introduced the ULEZ and then expanded it London-wide, we faced huge pressure from different quarters who wanted to obstruct and slow us down. But pressing on was the right thing to do. It's made an even bigger difference that we predicted. I'll continue to work with the Government, London boroughs and partners to continue building a healthier, greener, fairer London for everyone.”  

Professor Frank Kelly, Environmental Research Group, Imperial College London said: “London’s compliance with the UK’s annual mean nitrogen dioxide (NO₂) limit value in 2024 marks a truly remarkable turnaround for the city’s air quality. Just five years ago, research we undertook estimated it could take nearly two centuries to reach this milestone without decisive action. Thanks to the Ultra Low Emission Zone (ULEZ) and Mayor Khan’s other ambitious traffic management policies, London has achieved in a few years what was once thought impossible. While five other UK locations are still working towards compliance, London’s success demonstrates the power of bold, evidence-based interventions to deliver cleaner air.  We are now on the right path for pushing on and meeting the World Health Organisation’s (WHO) NO₂ guideline by 2030 which will achieve better health for all who live in this great city.”  

Sarah Sleet, CEO at Asthma + Lung UK, said: “This is an important step in the fight for Londoners to breathe clean air, and it’s great that this milestone has been reached ahead of target. It’s particularly significant for the 600,000 people living with a lung condition in Greater London and will help prevent the appallingly high rates of emergency admissions for respiratory conditions - around 100,000 in 2024/25 - as well as premature deaths.   

“For London to continue leading the way, we welcome Sadiq Khan’s commitment to bringing in stricter air quality standards in line with World Health Organization guidelines, and look forward to working with him to achieve this goal.”