Title: Investigating the impact of London’s Ultra Low Emission Zone on children’s respiratory health
Funder: Department of Health and Social Care

Abstract: Background: Strong evidence links urban air pollution to restrictions in children’s lung growth and development and other adverse effects, including increases in respiratory and allergy symptoms, respiratory infections, asthma, and health care use. Effective interventions are urgently needed that reduce air pollution and improve child health. Low Emission Zones (LEZ) are becoming widespread but are expensive to implement and of unproven health benefit. London has some of the worst air pollution in Europe. London’s Ultra Low Emission Zone (ULEZ) is the central component of London’s air quality strategy. Its implementation provides a unique opportunity to test the impact of a city-wide LEZ on children’s health. The intervention: The ULEZ is an area within which all vehicles must meet exhaust emission standards or pay a daily charge to travel. It will be implemented and paid for by Transport for London. Starting in 2019, the ULEZ will initially cover London’s central Congestion Charging Zone, an area bounded by the London Inner Ring Road, that includes the City of London plus adjacent areas of eight radially adjoining Boroughs. It is projected to deliver for central London by 2020 emission reductions of -49% for NOx; -47% for NO2; and -11% for PM10. Subject to consultation, the ULEZ will subsequently extend to include an inner London area (within London’s North and South Circular roads), and a London-wide area, for heavy vehicles only. Questions: 1) What is the impact of the ULEZ on children’s lung growth (the primary outcome)? 2) What is the impact of the ULEZ on secondary outcomes, including self-reported symptoms, respiratory infection, health care use and costs? 3) Does the ULEZ reduce health inequalities? 4) Is the ULEZ good value for money? Study design: Quasi-experimental study using a parallel cohort design. Population: 1520 children aged 6-9 yrs old, recruited in 26 London primary schools (school years 2, 3 and 4) in London’s Central Ultra Low Emission Zone. Intervention: Ultra Low Emission Zone Comparison: 1520 children aged 6-9 yrs old, recruited in 26 primary schools (school years 2, 3 and 4) in Luton, matched for ethnicity, deprivation and baseline air quality. Outcome: PRIMARY: Lung function growth (post-bronchodilator forced expiratory volume in one second (FEV1) measured by high quality spirometry at sequential annual school visits over four years. SECONDARY: Air quality, Forced vital capacity (FVC), quality of life, respiratory infections, physical activity, health care use, health costs. Sample size: To detect a 15ml/year FEV1 difference between central and outer London cohorts at 90% power and 0.05 significance requires children in each cohort, inflated to allow for clustering effect of schools, spirometry success, child and school attrition, and pre-specified sub group analyses, giving a total of 3120 children (60 children from 26 schools in each cohort). Duration: 6 years Air quality data: Modeled exposures by London Air Quality Network Data management: NIHR accredited Pragmatic Clinical Trials Unit Analysis: Interaction analysis controlling for effect modifiers (eg passive smoke; ethnicity); health economic cost consequence analysis.

Lay abstract: Air pollution from traffic in cities and towns is bad for people’s health. Children are especially vulnerable to traffic pollution. Pollution damages growing lungs, stunting their growth. If children enter adulthood with stunted lungs they are at risk of lifelong breathing disorders and earlier death. We urgently need to find effective ways to reduce pollution and prevent lifelong damage to children’s health. What is a Low Emission Zone? Low Emission Zones (LEZs) are areas of towns and cities where the entry of polluting traffic is discouraged. Although they are becoming common we don’t know whether they lead to better health. London has some of the worst air pollution in Europe. London’s Mayor will set up a new LEZ in 2019. He is calling it an ‘Ultra Low Emission Zone’ (ULEZ). This gives us a unique chance to find out if a city-wide LEZ improves air quality and limits damage to children’s lungs. What is London’s Ultra Low Emission Zone (ULEZ)? The ULEZ will be an area in London within which vehicles must meet strict exhaust emission standards or pay a daily fine. The ULEZ will initially cover an area in central London. By 2020 the ULEZ is predicted to have led to big improvements in air quality in that area, reducing nitrogen dioxide levels by half, and particulates (soot, mainly from exhaust) by ten percent. The ULEZ will probably extend in 2020 London-wide for heavy vehicles only, and in 2021 within London’s North and South Circular roads for light vehicles. How will we test whether the ULEZ improves health? We will compare the health of two large groups of primary school children (aged 6–9 years). One group will come from central London primary schools where the ULEZ will have most impact; the other from primary schools in Luton, a large town close to London with a broadly similar population, similar pollution levels, but no LEZ. We will make the two groups of children as similar as possible at the start of the study in terms of ethnic groups, deprivation, and pollution levels to which they are exposed. Every year for four years we will visit the children’s schools, starting the year before the ULEZ begins. We will measure accurately the growth of children’s lungs by asking them to blow into a machine called a spirometer. We will gather other data such as questionnaires on quality of life. At the end of the study we will, with their permission, obtain copies of their GP records to find out how often they’ve had infections, visited a GP or A&E, or been admitted to hospital for chest problems. We will monitor accurately the air pollution to which each child has been exposed over the four years, through the expertise of the world class team at Kings College, London. We need 26 primary schools in each of the two areas to take part, and from each of these schools we will recruit 60 children, giving a total of 1520 children in each area (3120 children in all) . We have allowed for drop outs over time, for example if children move away. With these numbers we will be able to detect very small differences in the volume of lungs between the two groups (about 15ml – the volume of an egg cup). We will also find out costs of implementing the ULEZ , money raised in fines, and estimate costs of health and health care in the two groups of children. We will calculate whether implementing the ULEZ is good value for money and whether LEZs should be used more widely.

Research activity codes: 3.2 INTERVENTIONS TO ALTER PHYSICAL AND BIOLOGICAL ENVIRONMENTAL RISKS
Health categories: RESPIRATORY