Seasonal distribution of airborne pollen in Ulsan, Korea in 2009-2010

To determine the peak dispersal times of allergenic pollen grains in Ulsan, Korea, we performed continuous airborne pollencounts at three stations (Sts. A, B, and C) in Ulsan from August 2009 to November 2010. Pollen grains were sampled usinga Durham sampler. Two peak pollen dispersal seasons were observed per year. The peak seasons generally coincidedwith the flowering period of anemophilous trees: Taxodiaceae (February), Alnus (March), Cupressaceae (April), Quercus,and Pinus (May), and with the flowering phase of herbs from August to November, e.g., Humulus, Artemisia, Gramineae,and Ambrosia from August through September. The highest concentration of airborne pollen was from Pinus (68%), followedby Quercus (15%), Alnus (6%), and Humulus (2%); whereas very low pollen concentrations were from Taxodiaceae,Cupressaceae, Artemisia, Gramineae, and Ambrosia (≤ 1% of the annual total airborne pollen concentration). Our findingsindicate that Alnus and Humulus pollen are major allergens whereas those of Pinus and Quercus are minor allergens.The concentration of Alnus pollen grains at St. C was over five times that at Sts. A and B. This finding implies that individualsliving at or near St. C are exposed to high concentrations of Alnus pollen before and after March, which is the floweringperiod of the alder tree. From August to September, individuals living at or near St. B are exposed to high concentrationsof Humulus pollen. Our study suggests that Alnus pollen may be the major aeroallergen causing pollinosis in the springat St. C and Humulus pollen may be the major aeroallergen in autumn at St. B.