London has met legal limits for nitrogen dioxide (NO2) pollution for the first time, according to new government data – nearly 200 years earlier than experts had once predicted.
Figures published by Defra show that in 2024 the capital’s air quality complied with the UK’s Air Quality Standards regulations. In 2019, researchers at King’s College London estimated it could take 193 years for London to reach this target without additional measures.
The report shows that last year there were no exceedances of the annual mean limit of 40µg/m³ for NO2 recorded in London by Defra’s Automatic and Rural Urban Network (AURN) or the UK Urban NO2 Network (UUNN). The highest reported concentration in the Greater London Urban Area was 36µg/m³.
Three non-AURN sites did show an exceedance of limit value but these monitors have long been excluded from the assessment as they don’t meet the same siting criteria as the AURN. These sites were at: Lambeth (Brixton Road), Lewisham (Loampit Vale) and Camden (Euston Road).
The improvement follows a series of air quality policies introduced since 2016 under Sadiq Khan, including the Ultra Low Emission Zone.
Compliance with ULEZ vehicle standards has risen from 39% in 2017 to 97% in 2024. Other measures include introducing more than 2,000 zero-emission buses and supporting the city’s growing electric vehicle charging infrastructure.
Defra’s data shows roadside levels of toxic NO2 have almost halved since Khan took office.
Public Health England previously estimated that air pollution contributes to around 4,000 premature deaths annually in London, while the Royal College of Physicians places the wider economic cost to the UK at £27 billion per year.
Professor Frank Kelly, Environmental Research Group, Imperial College London said: ‘London’s compliance with the UK’s annual mean 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.’
Photo: digital341
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