London's ULEZ Validated by 40% Drop in Air Pollution Deaths

When London's Ultra Low Emission Zone was first introduced in 2019, it was only 21 square kilometres in size, covering only the most central part of the city.

Today, after several expansions, the ULEZ covers an area of around 1,500 square kilometres, spanning all 32 London boroughs and encompassing the homes of more than nine million people.

The policy, which mandates that motorists with older, more polluting vehicles must pay a charge of £12.50 (US$16.71) to drive in the zone, was and continues to be a fairly radical policy.

While low-emission zones can be found elsewhere in Europe, never has one of such scale or standard been implemented.

It was introduced by Mayor of London Sadiq Khan as a public health measure after several shocking reports were released showing that poor air quality had played a contributing role in several deaths across the capital.

A new study, published by Imperial College London, reveals that the ULEZ has made a marked impact on this front. The research shows that from 2019 to 2024 deaths linked in air pollution dropped by 40%.

Khan, who has had to defend his policy for years, has celebrated this as a validation of ULEZ.

“The evidence is now overwhelming and unarguable: the bold action we have taken in London has reduced pollution, improved public health and saved lives," he says.

Cleaner transport delivers measurable emissions reductions

During the study period, concentrations of fine particulate matter fell by 28%, while nitrogen dioxide levels dropped by 41%.

According to the research, fine particulate matter can penetrate deep into the respiratory system and is associated with impaired lung development in children, an increased risk of lung cancer and higher rates of cardiovascular disease.

Updated assessment methods also indicate that prolonged exposure to pollution from urban transport presents a greater health risk than previously understood. The revised estimates show annual premature deaths declining from between 6,400 and 8,000 in 2019 to between 3,800 and 5,100 in 2024.

The research also strengthens evidence linking poor air quality with conditions including dementia, type two diabetes and childhood asthma, highlighting the wider health impacts of emissions beyond respiratory illness.

Lower emissions ease pressure on healthcare

Previous research from Imperial College London found that measures to curb transport emissions contributed to a 9.3% reduction in emergency hospital admissions for cardiac conditions. Admissions across all medical conditions within the ULEZ also fell by 5.1%.

According to Karen Bonner, Chief Nurse for the NHS in London, the findings demonstrate the long-term value of reducing air pollution. She says: "Thousands of Londoners are now living longer, healthier lives because the air they breathe is cleaner."

Karen adds that 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," she says.

Fewer pollution-related illnesses and hospital admissions could also help reduce demand on the UK's National Health Service, illustrating the broader economic benefits of cleaner energy and transport policies.

Air quality gains reinforce climate ambitions

Mete Coban, Deputy Mayor of London for Environment and Energy, highlighted the progress during Climate Group's Opportunity Summit, held as part of London Climate Action Week on 23 June before the publication of the research.

While welcoming the improvements in London's air quality, he stressed that the city must continue its efforts.

"When the mayor first got elected in 2016, experts and scientists told him it would take 193 years for us to reach the legal air quality limits here in London. We've done it in just nine years," Mete explains.

He says the city cleaned its air in nine years but remains committed to WHO guidelines. "Climate change doesn't impact everyone equally. It impacts those who've done the least to cause the crisis in the first place," Mete says.

He adds that half a million people in the city will never be able to breathe to their full capacity because of a crisis they did not cause. "Every time those toxins go in the air, it stunts the lungs of our children," he says.

The research was published during London Climate Action Week, which brings together business leaders, policymakers and investors to accelerate climate action and low-carbon investment.

During the event, HRH Prince William's Earthshot Prize published its Impact Report, marking five years since the initiative was launched.

According to the report, Earthshot Prize finalists had improved air quality in regions home to 600 million people, equivalent to around twice the population of the US.

"One day, people will look back at this decade and ask: when the evidence was clear, what did we do with it?" Prince William says.

"When we saw forests being restored, did we help restoration spread? When we saw clean air policies working, did we help other cities follow? When we saw the energy systems transform, did we fully commit? When we saw communities on the front line becoming leaders in resilience, did we stand beside them?"

He adds that the responsibility of this moment is to respond collectively. "The challenge can still feel immense but the proof is now in front of us. And history will ask what we did with it," he says.

Jane Burston, CEO of Clean Air Fund, says: "A 40% 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 reflects ongoing efforts by city leaders, civil society organisations and communities that have pushed for ambitious action."