Impact of the Ultra Low Emission Zone on lung function growth in children in London, UK: a prospective parallel cohort study

Traffic-related air pollution is a risk factor for lung disease and early mortality. Clean air zones are public health policy interventions used to reduce traffic-related air pollution in urban areas, but evidence of their health benefits is limited. We describe a natural experiment study evaluating the impact of the Ultra Low Emission Zone (ULEZ) in London, UK. The primary aim was to assess the impact of the ULEZ on children's lung function growth trajectories, by comparing forced expiratory volume in 1 s (FEV1) measurements over 5 years between children in London and Luton, UK.