1. Department of Respiratory Medicine, School of Medical Sciences, Örebro University , Örebro, Sweden
2. Department of Medical Sciences: Respiratory; Allergy and Sleep Research, Uppsala University , Uppsala, Sweden
3. Department of Public Health and Caring Science, Family Medicine and Preventive Medicine, Uppsala University , Uppsala, Sweden
4. Unit for Lung and Airway Research, Institute of Environmental Medicine, Karolinska Institutet , Stockholm, Sweden
5. Department of Respiratory Medicine and Allergology, Lund University , Lund, Sweden
6. Department of Public Health and Clinical Medicine, Division of Medicine, Umeå University , Umeå, Sweden