The atmospheric environment has not been monitored continuously in Phnom Penh but only in the period from 1996 to 2002 during which the observation by Japanese research group has been done on total suspended particulates (TSP), NO2 and SO2 1, 2). However, as to particulate matters, only the information at a city center was available. During past 10years after the election 1993, Cambodia economy has been growing very rapidly3,4). The number of automobiles has been also rapidly increasing and recently the number of automobiles including cars and motorcycles per population became similar to Thailand5). This inevitably leads to serious environmental problems but only a small potion of events has been recognized. Although the problems with the lack of infrastructure of the environmental monitoring instruments and network, it has to be clarified to recognize the present serious situation then start a step to the pollution control. In this study, suspended particulates were sampled at three sites in Phnom Penh including central downtown, residential area and peninsula between rivers Macon and Tonle Sap. At the central downtown, TSP was sampled both during day and night to discuss differences in concentrations and chemical compositions which may be related to the sort of emission source. Characteristics of anthropogenic emissions in Phnom Penh were discussed by comparing with other countries, or, Japan and Thailand. As chemical compositions analyzed, poly-cyclic aromatic hydrocarbons (PAHs) and heavy metals were chosen to discuss respectively influences of anthropogenic and soil emissions.