Title: Evaluating the life-course health impact of a city-wide system approach to improve air quality in Bradford, UK: A quasi-experimental study with implementation and process evaluation
Funder: Department of Health and Social Care

Abstract: BACKGROUND: The UK has high levels of air pollution, which costs the NHS and society around £20 billion a year. Poor air quality is a major cause of early death and illness. It has been linked to lung and heart disease in children and adults and low birth weight. During periods of poor air quality, health gets worse, leading to more hospital admissions and deaths. Children and the elderly are particularly affected by pollution. Poorer areas of the country have worse air quality and this increases inequalities in health. _x000D_ Thirty three local councils with high pollution levels have to put in place air quality plans which include Clean Air Zones. Bradford will introduce a Clean Air Zone in 2021 in order to reduce pollution using policies such as charging people for driving polluting vehicles. However, there is little evidence whether these policies improve air quality and health and what effect they might have on health inequalities._x000D_ _x000D_ AIMS: To evaluate the impact of a Clean Air Zone on air quality, health and health inequalities in the city of Bradford._x000D_ _x000D_ METHODS: We will explore changes in air quality in the city using regularly collected data that is already available on air pollution and will also collect additional data from 12 schools throughout the city. In addition, 240 children in these schools will help us collect data by using mobile air sensors for three months before the Clean Air Zone is put in place and for three months in the year after. The impact on lung, heart health and birth weight will be measured by comparing the health of over 500,000 Bradford residents in the three years before and three years after the Clean Air Zone is in place. The research will examine whether the impact is different for people from more deprived areas or different ethnic groups. This will use detailed information collected on 13,500 children who are part of the Born in Bradford study. We will look at whether the policy changes the way people choose to travel by conducting a survey with 4000 families. We will also conduct group discussions and interviews with key groups of people including businesses, transport companies, families, and pedestrians. These discussions will explore what may have helped or hindered the success of the policy and any unexpected effects. We will also explore if the Clean Air Zone is good value for money, e.g. do any improvements in health justify the costs._x000D_ _x000D_ PATIENT/PUBLIC INVOLVEMENT: 100 community members and two schools have been involved in developing our proposal and thinking about how to test if the policy will work and what effect it will have on the residents of Bradford. We have also worked closely with Bradford council and the UK Government department responsible for air quality nationally (DEFRA). Community, school and local authority representatives are part of our study team. They will be actively involved in the development and management of our research. _x000D_ _x000D_ DISSEMINATION: We will share our findings widely using a range of approaches depending on the audience. Researchers, policy and decision makers will receive academic papers, policy briefings, and be invited to events. We will communicate our research with communities through a series of short ‘in a nutshell’ reports publicised widely through social media channels, local media links, and engagement events. We will also develop materials for schools based on our findings to inspire and inform the next generation of researchers.

Lay abstract: BACKGROUND: Air quality is a major public health threat linked to poor birth outcomes, respiratory and cardiovascular disease, and premature mortality. Deprived groups, children and the elderly are disproportionately affected. Air quality-related illness costs the NHS and wider economy £20 billion/year. Due to illegal levels, the UK Government has issued directives to 33 local authorities to quickly reduce pollution, with charging ‘Clean Air Zones’ (CAZ), where polluting vehicles are charged to enter, a key component. However, evidence about the effectiveness of CAZs to improve health is scarce. Bradford will implement a CAZ in 2021 to reduce pollution, providing a natural experiment._x000D_ AIM: To evaluate the effectiveness, cost-effectiveness, inequality impacts and processes involved in implementation of the Bradford CAZ and learn lessons relevant to other local and national efforts to lower pollution. Objectives are to: assess 1) implementation, acceptability, fidelity (Workpackage[WP]1A), 2) change mechanisms (WP1B), and impacts on: 3) air quality (WP2), 4) health effects in children, adults and older adults (WP3A), 5) health inequalities (WP3B) and 6) value for money (WP4)._x000D_ RESEARCH QUESTIONS: Does the CAZ improve: life-course health outcomes; air quality; inequalities? Does the CAZ represent value for money? What are barriers to implementation and are there unintended/adverse consequences?_x000D_ METHODS: WP1A: 20 interviews with decision makers; 10 public focus groups and documentary analysis of key policies/reports will assess implementation barriers, acceptability and adverse/unanticipated consequences. WP1B: A population survey (n=4000) will assess changes in travel behaviour/attitudes 1 year post-implementation. WP2: Routine air quality measurements will be supplemented with data from low-cost, validated pollution sensors in 12 schools by pupils trained as citizen scientists (4 inside, 4 bordering and 4 distal to CAZ boundary, n=240 pupils). Pupils will carry sensors for 3 separate months in the year pre, and again in the year post-implementation. We will explore whether reductions in pollution vary by CAZ proximity. WP3A: Using a longitudinal routine health dataset of >500,000 Bradford residents we will conduct a quasi-experimental interrupted time series analysis comparing trends (3 years prior vs 3 years post) in respiratory health (assessed via emergency/GP attendances) with >90% power to detect a 5% reduction at 3 years. Results will be stratified by age (0-17 years; 18-64, 65+). Secondary outcomes include cardiovascular health and birth outcomes. WP3B: We will use the richly-characterised Born in Bradford cohort (13,500 children) to explore health inequalities in respiratory health using detailed socio-economic data. WP4 will adopt a multi-sectoral perspective to determine value for money._x000D_ TIMELINE: 60 months[M): Process and interim analyses (1 year post-implementation) by M37. 3 year follow-up and health economic evaluation by M60._x000D_ IMPACT/DISSEMINATION: The UK Government Joint Air Quality Unit has indicated its strong support, enabling policy links. For researchers, policy and decision makers we will produce academic papers, policy briefings and hold dissemination events. For communities, we will prepare lay summaries and publicise these widely, via our established social media channels, local media links, and engagement events. We will develop school citizen science curriculum materials to inspire young researchers.

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