1. Unit of Epidemiology and Medical Statistics, Department of Diagnostics and Public Health, University of Verona, 37134 Verona, Italy
2. National Heart and Lung Institute, Imperial College London, London SW3 6LR, UK
3. Biology and Genetics Section, Department of Neuroscience, Biomedicine and Movement, University of Verona, 37134 Verona, Italy
4. Respiratory Diseases Section, Department of Medicine, University of Verona, 37134 Verona, Italy
5. Department of Environmental and Prevention Sciences, University of Ferrara, 44121 Ferrara, Italy
6. Unit of Hygiene and Preventive, Environmental and Occupational Medicine, Department of Diagnostics and Public Health, University of Verona, 37134 Verona, Italy
7. Unit of Occupational Medicine, Department of Diagnostics and Public Health, University of Verona, 37134 Verona, Italy