Ulez Linked to Healthier Lungs in London's Children, Major Study Finds

A new study by Queen Mary University of London has found that the air quality improvements delivered by the ultra low emission zone are linked to healthier lungs in young people. Ulez – the daily charge for drivers of more polluting vehicles, introduced by Sadiq Khan in 2019 and widened to cover every London borough in 2023 – has been one of the most bitterly contested policies in the capital's recent history. This is the clearest evidence yet of what it has bought.

What the Ulez study actually found

Researchers monitored more than 3,400 children aged six to nine between 2018 and 2022, a window that straddles the introduction of Ulez in 2019. Before the zone came in, children in London had significantly smaller lungs than their counterparts in Luton. Over the five years that followed, lung growth in London accelerated, and by 2022 the capital's children were comparable to those in Luton.

Crucially, the scientists found the improvement was strongly linked to cleaner air rather than to other factors. Children's exposure to nitrogen dioxide, the pollutant pumped out by car exhausts, fell twice as fast in London as in Luton within five years of the zone being introduced.

Why the Luton comparison matters

Luton is not an arbitrary choice. The town has a similar mix of traffic pollutants to London but no clean air zone, which gives researchers something close to a real-world control group: two populations of children breathing comparable traffic emissions, one of which then had a charging zone imposed on it and one of which did not.

That design is what lifts the findings above the correlation-versus-causation argument that dogs air quality research, and it is why the study lands as more than another line in the row over motoring charges. It also speaks to the UK's widening health divide, in which where you grow up increasingly shapes how healthy you are.

What the Ulez findings mean for other cities

The report's joint senior author, Chris Griffiths, professor of primary care at Queen Mary University of London and the University of Oxford, framed the results as a template rather than a local curiosity.

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For Hartshorn, the findings are personal rather than political. "This is fantastic news. It gives me real reassurance that it is never too late to clean up the air," she told Metro. "To hear that any damage my children may have had is outweighed by Ulez is such a massive relief." Nine years after she read the article that started all of this, the lungs of London's children have caught up.