1. Public Health & Policy, London School of Hygiene and Tropical Medicine, London, UK
2. Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK
3. MRC/CSO Social & Public Health Sciences Unit, University of Glasgow, Glasgow, UK
4. Social and Environmental Research, London School of Hygiene and Tropical Medicine, London, UK
5. Department of Public Health, Environments and Society, Faculty of Public Health and Policy, London School of Hygiene and Tropical Medicine, London, UK
6. MRC/CSO Social and Public Health Sciences Unit, University of Glasgow, Glasgow, UK