K Karatzas1, M Riga1, U Berger2, M Werchan3, O Pfaar4,5, K C Bergmann3. 1. Department of Mechanical Engineering, Environmental Informatics Research Group, Aristotle University, Thessaloniki, Greece. 2. Aerobiology and Pollen Information Research Unit, Department of Oto-Rhino-Laryngology, Medical University of Vienna, Vienna, Austria. 3. Foundation German Pollen Information Service, Berlin, Germany. 4. Department of Otorhinolaryngology, Head and Neck Surgery, Universitätsmedizin Mannheim, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany. 5. Center for Rhinology and Allergology, Wiesbaden, Germany.