Effect of land cover and wind on airborne Olea pollen

The study of the potential sources of allergenic pollen is widely used to estimate exposure risk to the high con-centrations of airborne particles. From this point of view, the land cover of the area surrounding the samplingstation (pollen trap) has a decisive impact on local airborne pollen counts. The study of the vegetation mustbe combined with the meteorological parameters and, in particular, with the wind, recognized as being one ofthe most important factors in airborne pollen diffusion. In order to studyOleapollen transport, we correlatethe pollen records with the area covered by olive groves and the wind directions and intensity.Oleapollentype was selected for the great presence of olive trees in this area and for its high allergenic potential. Thestudy was carried out in Florence (Arno Valley, Italy) over a period of five years (2011 – 2015). Pollen datawere furnished by Regional agency for environmental protection of Tuscany (ARPAT) whose pollen samplinghas been carried out through the use of a volumetric Hirst-type spore trap located at 20 m a.s.l., in the north-western area of the city. Meteorological data concerning wind were supplied by the weather station of theUniversity of Florence, about 2 km from the ARPAT monitoring station, in the north-eastern area of the city.A buffer of 10 km in radius surrounding the volumetric sampler was created using GIS software; olive grovesof this area were detected through the use of orthophotos furnished by the Territorial and Environmental Infor-mation System of Tuscany. The area surrounding the pollen monitoring station showed a widespread presenceof olive groves, in particular in the south-eastern and south-western parts from the sampling point (more than30% of the southern buffer area) and in the north-eastern area from the sampling point (more than 20% of theeastern buffer area); the lowest presence of olive trees is shown in the north-western area from the samplingstation (less than 10%). Regarding the statistical analysis betweenOleapollen records and wind directions,the greatest correlation is shown when the wind blows from the north-west.Oleapollen values also showeda strong negative correlation with wind intensity. The greatest contribution ofOleapollen is given by thenorthwestern winds, despite the low abundance of olive groves in this area. This conclusion hints at a pollendiffusion from a greater distance than that considered for this work and the influence of the topographicalfeatures of the study area.