1. Pulmonology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia
2. Department of Mathematics, Faculty of Sciences, Centre of Mathematics, University of Porto, Porto
3. Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto
4. EPIUnit, Institute of Public Health, University of Porto, Porto, Occupational Health, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia
5. EPIUnit, Institute of Public Health, University of Porto, Porto
6. Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, ICVS/3B's, Portugal Government Associate Laboratory, Braga/Guimarães
7. Public Health Department, Agrupamento de Centros de Saúde do Porto Oriental, Porto, Portugal
8. Pulmonology Department, Centro Hospitalar de Vila Nova de Gaia/Espinho, Vila Nova de Gaia, Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, EPIUnit, Institute of Public Health,
University of Porto, Porto