1. 2nd Pulmonary Department, ATTIKON University Hospital, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
2. Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece
3. Pulmonary Department, G. Papanikolaou Hospital, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
4. School of Chemical Engineering, National Technical University of Athens, Athens, Greece
5. Department of Primary Care & Public Health Sciences and Environmental Research Group, King’s College, London, UK