1. Respiratory Epidemiology and Public Health Group; Imperial College London; National Heart and Lung Institute; London UK
2. Occupational and Environmental Medicine; Imperial College London; National Heart and Lung Institute; London UK
3. Occupational and Environmental Medicine; Umeå University; Umeå Sweden
4. Department of Medical Sciences: Respiratory Medicine and Allergology; University of Uppsala; Uppsala Sweden
5. Krefting Research Centre; Institute of Medicine; University of Gothenburg; Gothenburg Sweden
6. CfA - The Centre for Allergy Research; Karolinska Institute; Stockholm Sweden
7. Skin and Allergy Hospital; Helsinki University; Helsinki Finland
8. Department of ORL-HNS; Temple University; Philadelphia PA USA
9. Odense University Hospital; Odense University; Odense Denmark
10. Department of Immunology, Rheumatology and Allergy; Medical University of Lodz; Lodz Poland
11. Department of Allergology and Clinical Immunology; Medical University of Silesia; Katowice Poland
12. Department of Allergy and Immunology; Southampton General Hospital; Southampton UK
13. Department of Otorhinolaryngology; Academic Medical Center; Amsterdam The Netherlands
14. University of Ghent; Ghent Belgium
15. Division of Ear, Nose, and Throat Diseases; Karolinska Institute; CLINTEC; Stockholm Sweden
16. Department of Pediatric Pneumonology and Immunology; Charité-Universitätsmedizin Berlin; Berlin Germany
17. IUF - Leibniz Research Institute for Environmental Medicine; Düsseldorf Germany
18. Faculty of Medicine; University of Coimbra; Coimbra Portugal
19. Unit 700 - Epidemiology; INSERM; Paris France
20. Université Paris-Diderot Paris 7; Paris France