A qualitative and quantitative analysis of airborne pollen collected with a Cour trap in Trieste (NE Italy) is presented. The behaviour of 30 pollen types, corresponding to 81.4% of the total collected pollen, was studied. Average results for the period 1987-1996 are presented, together with the highest values found. The highest mean weekly concentrations of total collected pollen are recorded from middle February to middle July, when approximately 86% of the annual total pollen was collected. During the year several peaks occur, principally due to Cupressaceae in early March, and to Quercus, Ostrya, Moraceae, Urticaceae, Pinus and Grarnineae in May. The variation in the annual total concentration over the years shows extraordinary concentrations of Abies, Picea, Fagus and Olea pollen in 1992. Most pollen types are from woody species (56.6%), while a minor contribution comes from herbaceous species (24.8%). The mean composition of the atmospheric pollen spectrum of Trieste reflects well the natural woodlands surrounding the town, and its ornamental and ruderal floras.
