Characterization of the number and chemical size distribution as well as hygroscopicity of fine and ultrafine particles in Beijing, China

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The project described here is a joint investigation between the State Key Laboratory for Atmospheric Environmental Simulation at the Peking University, Beijing, China, and the Institute for Tropospheric Research, Leipzig, Germany. The major goal of this three-year project is to determine number size distributions, hygroscopic properties, and chemical size distributions of the highly polluted urban aerosol in Beijing. Beijing is a town with more than 15 million inhabitants and it is in the period of transition to a modern city. The aerosol in Beijing consists mainly of three types of particles, the carbonaceous aerosol from domestic coal burning, the emission from the drastically increasing car, bus, and truck traffic, and the fine dust from desert regions in China. The combination of these aerosols in combination with secondary aerosol formation due to the high photochemistry creates a visible particulate air pollution. Since sizedependent aerosol properties especially in the size range smaller than 100 nm are unknown for Beijing, an estimate of the possible strong influence of the particulate pollution on human airway diseases cannot be made yet. To understand better the impact of the Beijing urban aerosol on human health in future, sizedependent physical and chemical aerosol properties down to the ultrafine size range has to be investigated. Specifically, numer size distributions down to 3 nm, hygroscopic properties in the size range 20-250 nm, and chemical composition down to 10 nm in diameter will be determined. The number size distribution will be operated on a continuous base and will provide diurnal, weekly, and seasonal variations over a two year period, while the other properties are measured during two intensive campaigns, one in summer and one in winter time.