1. Comprehensive Pneumology Center, Institute of Lung Biology and Disease, Helmholtz Zentrum München—German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg/Munich, Germany
2. Institute of Epidemiology, Helmholtz Center Munich—German Research Center for Environmental Health, Ingolstaedter Landstrasse 1, D-85764 Neuherberg/Munich, Germany
3. Directorate for Health, Consumers and Reference Materials, Joint Research Centre, European Commission, Via E. Fermi 2749, I-21027 Ispra, Varese, Italy
4. Institute of Anatomy, University of Bern, Baltzerstrasse 2, CH-3012 Berne, Switzerland