Taiwan is located downwind of the transport paths of the East Asian air pollution and the Southeast Asian biomass burning. Regional meteorological conditions are suitable for the transport of air pollutants (e.g. acidic pollutants, dusts, and biomass burning emissions) from upwind source regions to Taiwan. Due to the economy booming in Asia, regional fossil fuel consumption and industrial emission increase dramatically. Accordingly, the influence of the long-range transport of air pollutants is also increasing. To investigate the impact of long-range transported hazardous air pollutants (HAPs) on Taiwan’s environmental quality, Taiwan EPA drew up this project to achieve the following goals: feasibility assessment of the routine monitoring of long-range transported HAPs; establishment of the monitoring technology of long-range transported HAPs; international collaboration on the study of the impact of long-range transported air pollutants on Taiwan’s environment. Because there are many HAPs, mercury and dioxins were selected for evaluation of routine monitoring in this study. In 2008-2009, a total of 19 intensive observation periods (IOPs) were conducted at the following sites: Mazu, Pengjiayu, Fugueijiao, Mt. Bamboo, Mt. Hehuan, Hengchun, Lanyu, and Dongsha. Atmospheric mercury and dioxins were measured during each IOP. Each IOP lasted at least 7 days. Except at Fugueijiao and Mt. Hehuan where only 1 IOP was conducted, respectively, at least 2 IOPs were conducted at each of the other sites to investigate the seasonal variation in long-range transport. Concentrations of atmospheric mercury and dioxins were 1.06-2.97 ng m-3 and 0.42-390 fg-I-TEQ m-3, respectively. Seasonal variations in concentrations of both pollutants were observed, usually with lower concentrations in summer and higher concentrations in winter and spring. The seasonal variation in pollutant concentrations was related to the seasonal variation in air mass origins. In summer, the prevailing southwest monsoon brought clean marine air masses with lower concentrations of mercury and dioxins. On the other hand, in winter and spring, the prevailing northeast monsoon brought continental air masses, which contained higher HAPs concentrations. This study also investigated the chemical composition, including water-soluble ions and metal elements, of Mt. Lulin aerosol samples (PM 2.5 and PM 2.5-10). In 2008-2009, SO42- and NO3- were the major anions, while NH4+ was the major cation. Fe, Al, and Mg were the major metal elements. Pb was the most frequently detected hazardous metal element. Regarding the progress of international collaboration, besides the participation of relevant international conferences, the co-measurement of atmospheric mercury with Japanese researchers at Mt. Fuji weather station in Aug. 10-18, 2008 and the measurement of mercury and dioxins at Gosan in Jeju Island, Korea in Mar. 26-Apr. 17, 2009 were the principal tasks performed.

long-range,transport,,atmospheric,mercury,,dioxins,,water-solubleions,,metal,elements