1. Swiss Tropical and Public Health Institute, Basel, Switzerland
2. University of Basel, Basel, Switzerland
3. Department of Epidemiology, Leibnitz Institut for Environmental Medicine at the Heinrich-Heine University (IUF), Düsseldorf, Germany
4. Division of Pulmonary Medicine, University Hospitals of Geneva, Geneva, Switzerland
5. Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA