A study of airborne Ulmaceae pollen in Modena (northern Italy)

We examined Ulmaceae airborne pollen at the Modena-Geophysical Observatory monitoring station in 1993. The pollen trap was placed 15 m above the ground. 365 daily slides were fully analyzed to obtain daily and bi-hourly pollen concentrations. Morphological analysis on native and introduced Ulmaceae pollen was also conducted between February 3rd and May 17th. Five pollen types were identified: Celtis cf. australis, Ulmus glabra, Ulmus cf. laevis, Ulmus cf. minor, and Ulmus minor/laevis. Pollen concentrations and percentages showed that the Elm family contributed little pollen to the air (about 1% of the total pollen recorded), Ulmus and Celtis being 0.9% and 0.04%, respectively. The maximum levels were 30 p/m3/24 hr and 118 p/m3/ 2 hr (Ulmus) and 4 p/m3/24 hr and 13 p/m3/2 hr (Celtis). The highest levels of Ulmus were during the morning and afternoon, while the afternoon was highest for Celtis. In general, Ulmaceae trees appear worth planting in urban areas, but Celtis pollen should also be monitored at human height.