1. Department of Dermato-Allergology; National Allergy Research Centre, Copenhagen University Hospital Gentofte; Ledreborg Allé 40, 1 DK-2820 Gentofte Denmark
2. Department of Dermato-Allergology, Allergy Clinic; Copenhagen University Hospital Gentofte; Niels Andersens Vej 65 DK-2900 Hellerup Denmark
3. Department of Environmental Science; Aarhus University; Frederiksborgvej 399 DK-4000 Roskilde Denmark