1. Department of Orthopaedic Surgery; Aarhus University Hospital; DK-8000 Aarhus Denmark
2. Institute of Environmental Medicine; Karolinska Institutet; 171 77 Stockholm Sweden
3. Department of Dermato-Allergology; National Allergy Research Centre, Gentofte University Hospital; DK-2900 Hellerup Denmark
4. Department of Dermato-Allergology; Gentofte University Hospital; DK-2900 Hellerup Denmark
5. Department of Applied Environmental Science; Stockholm University; SE-10691 Stockholm Sweden
6. Department of Mechanical Engineering; Technical University of Denmark; DK-2800 Kongens Lyngby Denmark