1. Department of Epidemiology, School of Medicine in Katowice, Medical University of Silesia in Katowice, Katowice, Poland;
2. ADAMED Group, Czosnow, Poland;
3. Canadian Centre for Health and Safety in Agriculture, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada;
4. Department of Medicine, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada;
5. Polish Respiratory Society, Warsaw, Poland