Jemima Hartshorn, who founded the Mums for Lungs campaign in London in 2017 after learning about the dangers of air pollution to her newborn son, says she has been vindicated by a major new study on the health benefits of the Ultra Low Emission Zone (Ulez). The study, led by Queen Mary University, found that air quality improvements from Ulez are linked to healthier lung development in children. The researchers discovered that children's lung size and health accelerated since Ulez was introduced in 2019.
Study Details and Findings
The team at Queen Mary University monitored more than 3,400 children aged six to nine from 2018 to 2022. Before Ulez was implemented, children in London had significantly smaller lungs compared to those in Luton, a town with a similar mix of traffic pollutants but no clean air zone. However, the data collected over five years indicated that London children's lung size and health both accelerated and improved as the zone was rolled out. By 2022, the lungs of children in the capital became comparable to those in Luton.
The scientists found that the boost in lung growth was strongly related to air quality improvements. Within five years of Ulez's introduction, London children's exposure to nitrogen dioxide (NO2), a car exhaust pollutant, fell twice as fast, and more than twice as much, compared with children in Luton. The study also measured forced expiratory volume in one second (FEV1), a key indicator of lung and airway function. Over the course of the study, London children's FEV1 increased by 10ml per year more than children in Luton, allowing them to catch up by the end of the five-year period.
Expert and Campaigner Reactions
Chris Griffiths, professor of primary care at the University of Oxford and at Queen Mary University of London, and joint senior author of the report, said: 'Traffic pollution in cities damages children's health and development. We provide the strongest evidence yet on how these harms can be prevented. Ambitious clean air zones should be considered a priority for cities globally with traffic-related air pollution.'
Jemima Hartshorn, who has two children aged 7 and 10, described the results as 'super exciting' and said they show that 'damage inflicted by air pollution can be compensated by cleaner air.' She added: 'This is more than ever a call to action for city leaders and the new Prime Minister Andy Burnham, who knows that air pollution is stunting children's lungs and stifling our economy. If he wants to truly set Britain on path to growth, we need cleaner air, less diesel, a phase out of domestic burning, and real action to clean out our cities and towns.'
Mayor's Response and Broader Impact
London Mayor Sadiq Khan, who spearheaded Ulez, celebrated the findings, saying they show the 'extraordinary difference that cleaner air can make.' Khan told Metro: 'No child should have their future health limited by the air they breathe. Today's landmark independent report provides yet more compelling evidence that the London ULEZ, the world's biggest clean air zone, is working and has been a huge success – showing it's never too late to act against the devastating effects of air pollution.'
Despite the praise from climate campaigners, Ulez has faced significant backlash from some drivers. Critics argue the daily fee negatively impacts people who rely on vehicles for transport in outer London boroughs, as well as low-income households, commuters, and small businesses using older vans. Khan said he had 'refused to stand by' and watch air pollution damage Londoners' health, despite opposition from 'a vocal minority backed by vested interests.' He added: 'This research proves we were right to act and reinforces my decision to extend the benefits of cleaner air to every child in London.'
Clinical Implications and Next Steps
The study, which recruited children from 84 primary schools in London and Luton, also found that the proportion of children with clinically impaired lung function fell from 14% to 9% in London, compared with a fall from 9% to 7% in Luton. Ian Mudway, associate professor in the School of Public Health at Imperial College London and joint senior author of the report, said: 'Air pollution is a global issue. If we want to improve the lives of children living in high-traffic urban environments, we need bold and ambitious measures. Our data demonstrates that clean air zones can be an effective public health intervention to prevent damage to developing lungs.'
Experts warn that children who do not have fully developed lungs by early adulthood face higher risks of asthma, cardiovascular and metabolic disease, as well as premature death as adults. The findings provide strong evidence that clean air zones can mitigate these risks, offering a clear directive for cities worldwide to prioritize such measures.
