Int J Biometeorol (2005) 49:139–145 DOI 10.1007/s00484-004-0229-z ORIGINAL ARTICLE Athanasios Damialis · Dimitrios Gioulekas · Chariklia Lazopoulou · Christos Balafoutis · Despina Vokou Transport of airborne pollen into the city of Thessaloniki: the effects of wind direction, speed and persistence Received: 20 January 2004 / Revised: 21 July 2004 / Accepted: 28 July 2004 / Published online: 19 October 2004  ISB 2004 Abstract We examined the effect of the wind vector analyzed into its three components (direction, speed and persistence), on the circulation of pollen from differ- ent plant taxa prominent in the Thessaloniki area for a 4-year period (1996–1999). These plant taxa were Am- brosia spp., Artemisia spp., Chenopodiaceae, Corylus spp., Cupressaceae, Olea europaea, Pinaceae, Platanus spp., Poaceae, Populus spp., Quercus spp., and Ur- ticaceae. Airborne pollen of Cupressaceae, Urticaceae, Quercus spp. and O. europaea make up approximately 70% of the total average annual pollen counts. The set of data that we worked with represented days without pre- cipitation and time intervals during which winds blew from the same direction for at least 4 consecutive hours. We did this in order to study the effect of the different wind components independently of precipitation, and to avoid secondary effects produced by pollen resuspension phenomena. Factorial regression analysis among the summed bi-hourly pollen counts for each taxon and the values of wind speed and persistence per wind direction gave significant results in 22 cases (combinations of plant taxa and wind directions). The pollen concentrations of all taxa correlated significantly with at least one of the three wind components. In seven out of the 22 taxon-wind di- rection combinations, the pollen counts correlated posi- tively with wind persistence, whereas this was the case for only two of the taxon-wind speed combinations. In seven cases, pollen counts correlated with the interaction effect of wind speed and persistence. This shows the importance of wind persistence in pollen transport, particularly when weak winds prevail for a considerable part of the year, as is the case for Thessaloniki. Medium/long-distance pollen transport was evidenced for Olea (NW, SW directions), Corylus (NW, SW), Poaceae (SW) and Populus (NW). Keywords Pollen forecast · Pollen dispersal · Wind direction · Wind speed · Wind persistence Introduction Research on airborne pollen dispersion and transport at- tracts the interest of many scientists worldwide (Solomon and Mathews 1978; Solomon 1984; Rantio-Lehtimäki 1994; Laaidi 2001; Gioulekas et al. 2003). This is mainly due to the fact that pollen grains are frequently implicated in respiratory allergy symptoms, but also because of the high economic importance associated with some of them. For these reasons, forecasting of the main pollen season is a common pursuit for many researchers (Munuera Giner et al. 1999; Laaidi 2001; Adams-Groom et al. 2002; Gioulekas et al. 2003; Laaidi et al. 2003; Van de Water et al. 2003; Vazquez et al. 2003). The dispersal and transport of pollen from numerous taxa are influenced by several meteorological factors, such as wind, rainfall, air temperature, and relative hu- midity (Solomon and Mathews 1978; Solomon 1984; Mandrioli 1990; Keynan et al. 1991; Adams-Groom et al. 2002; Vazquez et al. 2003; Gioulekas et al. 2004). Wind is a major factor affecting pollen air circulation (Solomon and Mathews 1978; Solomon 1984; Cour et al. 1999; Silva-Palacios et al. 2000) and is associated with many cases of conjunctivitis and asthma (Laaidi 2001). How- A. Damialis ( ) ) · D. Vokou Department of Ecology, School of Biology, Aristotle University, UPB 119, 54124 Thessaloniki, Greece e-mail: dthanos@bio.auth.gr Tel.: +30-2310-998323 D. Gioulekas Department of Pulmonary Medicine, School of Medicine, Aristotle University, Thessaloniki, Greece C. Lazopoulou Department of Accountancy, School of Management and Business Economy, Technological Educational Institute, Thessaloniki, Greece C. Balafoutis Department of Meteorology–Climatology, School of Geology, Aristotle University, Thessaloniki, Greece