1. Centre for Research in Environmental Epidemiology, Barcelona, Spain
2. Municipal Institute of Medical Research, Hospital del Mar, Barcelona, Spain
3. CIBER Epidemiología y Salud Pública, Barcelona, Spain
4. Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
5. Institut national de la santé et de la recherche médicale, U780, Epidemiology and Biostatistics, Villejuif, France
6. Occupational and Environmental Medicine, Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden
7. Genes and Disease Program, Center for Genomic Regulation, Barcelona, Spain
8. Department of Health and Experimental Sciences, University Pompeu Fabra, Barcelona, Spain
9. Respiratory Epidemiology and Public Health Group, National Heart and Lung Institute and
10. Epidemiology and Public Health, Imperial College, London, United Kingdom
11. Department of Medical Sciences, Uppsala University and University Hospital, Uppsala, Sweden
12. Department of Medical Sciences, Respiratory Medicine and Allergology, Uppsala University, Uppsala, Sweden
13. Helmholtz Zentrum München, German Research Centre for Environmental Health, Munich, Germany
14. Institute of Epidemiology, Helmholtz Zentrum München, Munich, Germany
15. National School of Public Health, Athens, Greece