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When London introduced its Ultra Low Emission Zone (Ulez) in April 2019, the aim was to cut traffic pollution and protect the health of the people breathing it. For years, evidence of its impact has largely come from roadside monitors, exhaust emissions and changing vehicle numbers. Seven years on, researchers are increasingly able to measure something more tangible: what cleaner air appears to be doing to people’s bodies.
The latest findings come from a five-year study involving more than 3,400 primary school children in London and Luton. Researchers led by Queen Mary University of London recruited children aged six to nine from schools within or bordering the original central London Ulez and compared them with children in Luton, a similar urban area without a comparable clean-air zone.
The children underwent annual lung-function tests between 2018 and 2022, allowing scientists to compare how their lungs developed before and after Ulez was introduced.
Before the scheme came into force, the London children had lower lung capacity than those in Luton and were exposed to higher levels of nitrogen dioxide (NO₂), a harmful pollutant strongly associated with vehicle exhausts. After 2019, however, NO₂ levels fell faster in London while the children’s lungs grew more rapidly.
