London’s Ultra Low Emission Zone Linked to Faster Lung Growth in Children

A five-year prospective cohort study (the CHILL study) compared lung development in 3,414 primary-school children aged 6-9 from London and the nearby town of Luton. Annual spirometry from 2018 to 2022 showed that London children, who entered the study with smaller forced expiratory volume in one second (FEV1) than their Luton peers, experienced accelerated growth after the 2019 introduction of the Ultra Low Emission Zone (ULEZ). By the end of follow-up, average FEV1 and overall lung capacity were essentially identical in the two groups, and the share of children with clinically impaired lung function fell from 14 % to 9 % in London versus 9 % to 7 % in Luton.

The ConversationIntroduction of London’s Ultra Low Emission Zone linked to improved lung growth in children Impact of ULEZ on children’s lung function growth London ULEZ linked to improved lung growth in children Clean air zone linked to improved lung development in children CNNLondon’s ULEZ linked to improved lung growth in children Scientists ‘stunned’ by children’s lungs after ULEZ introduced Scientists find unexpected recovery in children’s lungs after ULEZ cuts pollution BBC News

London’s ULEZ, first applied to central boroughs in April 2019, imposes a daily charge on vehicles that fail to meet strict emissions standards. The scheme was expanded to outer London in 2021 and to the whole capital in August 2023. Designed to curb nitrogen dioxide (NO2) and fine-particle emissions from traffic, the policy has been a focal point of public-health debate. The CHILL study was conceived to test whether the resulting air-quality improvements could translate into measurable health benefits for children in a high-traffic urban environment.

Electrek

• Participants: 1,664 London children, 1,750 Luton children.

Introduction of London’s Ultra Low Emission Zone linked to improved lung growth in children

• Baseline: London children’s average FEV1 was ~38 mL lower; modeled residential NO2 exposure was ~19 µg m?³ higher.

The Conversation

• Pollution change: Over the five-year period, NO2 levels in London fell more than twice as fast as in Luton (?3.8 µg m?³ yr?¹ vs 1.8 µg m?³ yr?¹).

BBC News

• Lung-function change: Annual FEV1 growth was about 10 mL yr?¹ greater in London, yielding a net increase of ~10 mL per year relative to Luton.

The Conversation

• Clinical impairment: London’s proportion of children with impaired lung function dropped from 14 % to 9 %; Luton’s fell from 9 % to 7 %.

London’s ULEZ linked to improved lung growth in children

Some independent experts caution against attributing the entire improvement to the ULEZ. Stephen Burgess, professor of biostatistics at the University of Cambridge, argued that pandemic-related reductions in traffic may have contributed to the gains and that the causal link remains “more questionable.” Kevin McConway, emeritus professor of applied statistics at the Open University, highlighted the study’s limited geographic scope, noting that results from only two towns cannot definitively isolate the ULEZ effect. Both stress the need for additional research in other cities and for analyses that control for changes in children’s activity patterns.

CNN

The authors present a strong association between falling NO2 exposure and faster lung growth, yet alternative explanations have been offered, including the COVID-19 pandemic’s impact on traffic and possible shifts toward walking or cycling after the ULEZ rollout. The study relied on modelled residential exposure and did not capture non-residential or indoor pollutant levels, leaving uncertainty about the full exposure profile.

The Conversation