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In this study, a regional air quality model system (RAQMS) was applied to investigate the spatial distributions and seasonal variations of atmospheric aerosols in 2006 over East Asia. Model validations demonstrated that RAQMS was able to reproduce the evolution processes of aerosol components reasonably well. Ground-level PM10 (particles with aerodynamic diameter a parts per thousand currency sign10 A mu m) concentrations were highest in spring and lowest in summer and were characterized by three maximum centers: the Taklimakan Desert (similar to 1000 A mu g m(-3)), the Gobi Desert (similar to 400 A mu g m(-3)), and the Huabei Plain (similar to 300 A mu g m(-3)) of China. Vertically, high PM10 concentrations ranging from 100 A mu g m(-3) to 250 A mu g m(-3) occurred from the surface to an altitude of 6000 m at 30A degrees aEuro"45A degrees N in spring. In winter, the vertical gradient was so large that most aerosols were restricted in the boundary layer. Both sulfate and ammonium reached their highest concentrations in autumn, while nitrate reached its maximum level in winter. Black carbon and organic carbon aerosol concentrations reached maximums in winter. Soil dust were strongest in spring, whereas sea salt exerted the strongest influence on the coastal regions of eastern China in summer. The estimated burden of anthropogenic aerosols was largest in winter (1621 Gg) and smallest in summer (1040 Gg). The sulfate burden accounted for similar to 42% of the total anthropogenic aerosol burden. The dust burden was about twice the anthropogenic aerosol burden, implying the potentially important impacts of the natural aerosols on air quality and climate over East Asia.