When Sadiq Khan introduced London's ultra-low emission zone (Ulez) over seven years ago, he was accused of waging war on motorists. Now, a study shows the city's children are breathing better, and the critics have gone suspiciously quiet.

The Ulez, which started in central London in 2019 and expanded to cover the entire city by 2023, making it the world's largest clean-air zone, faced fierce opposition. Detractors claimed it was a blind pursuit of a policy that might not even work, and all mainstream political parties, including Khan's own Labour, were against it. But as Khan notes, those critics have since fallen silent, and for good reason.

A mountain of evidence now shows the Ulez has slashed air pollution across London. Research from Imperial College London earlier this year found that between 2019 and 2024, estimated deaths linked to air pollution in the capital fell by around 40%. Now, a new independent study from Queen Mary University of London reveals the zone is also improving the lungs of London's children, with better lung size and function.

Khan, who calls the Ulez his hardest decision as mayor, insists it wasn't about attacking motorists but about ensuring children no longer breathe dangerous levels of pollution. The study, he says, shows the policy is working, and the city's youngest residents are reaping the benefits. Who knew that cleaner air might be good for you?