Aerosol particles play and important role in urban air quality and global climate. Poor air quality caused by high concentrations of particulate matter is one of the greatest health concerns for humans worldwide. The large cities are in the focal point of this risk due to the coincidence between the high fraction and large density of population on one side and intensive pollution sources on the other side. The role of aerosol in the global radiation budget and cloud formation/water cycling have been also recognized. My scientific interests cover all aspects of tropospheric aerosol research, implications on climate, human health, and built environment, especially studies on urban-type aerosol.