[1] Univ Ghent, Upper Airways Res Lab, Dept Otorhinolaryngol & Logopaed Audiol Sci, B-9000 Ghent, Belgium
[2] Univ London Imperial Coll Sci Technol & Med, Natl Heart & Lung Inst, Resp Epidemiol & Publ Hlth Grp, London, England
[3] Univ Amsterdam, Acad Med Ctr, Dept Otorhinolaryngol, NL-1105 AZ Amsterdam, Netherlands
[4] Univ Gothenburg, Dept Internal Med, Krefting Res Ctr, Gothenburg, Sweden
[5] Karolinska Inst, CLINTEC, Div ENT Dis, Stockholm, Sweden
[6] Uppsala Univ, Akad Sjukhuset, Dept Med Sci Resp Med & Allergol, Uppsala, Sweden
[7] Odense Univ Hosp, Dept Occupat & Environm Med, DK-5000 Odense, Denmark
[8] Charite, Dept Pediat Pneumol & Immunol, D-13353 Berlin, Germany
[9] Tech Univ Munich, Dept Dermatol & Allergy Biederstein, D-8000 Munich, Germany
[10] Univ Dusseldorf, Inst Umweltmed Forsch, Dusseldorf, Germany
[11] Med Univ Lodz, Dept Immunol Rheumatol & Allergy, Lodz, Poland
[12] Med Univ Silesia, Dept Epidemiol, Katowice, Poland
[13] CNR, Ist Biomed & Immunol Mol, Palermo, Italy
[14] Southampton Univ Hosp Trust, Southampton, Hants, England
[15] Hosp Univ Coimbra, Pulmonol Unit, Coimbra, Portugal
[16] Finnish Inst Occupat Hlth, Helsinki, Finland