Exposure assessment studies for particulates have been conducted in several U.S. and European cities; however, exposure data remain sparse for Asian populations whose cultural practices and living styles are distinct from those in the developed world. This study assessed personal PM(10) exposure in urban residents and evaluated PM(10) indoor/outdoor levels in communities with different characteristics. Important factors of personal PM(10) exposure in Taiwan were explored. Sampling was conducted in 6 communities in Taiwan, two in each of the three major metropolitan areas. Up to nine non-smoking volunteers in each community carried personal samplers for 24 h. The geometric means (GM) of PM(10) in personal, indoor and outdoor samples were 76.3 microg/m(3) (geometric standard deviation, GSD=1.8), 73.4 microg/m(3) (GSD=1.5), and 85.8 microg/m(3) (GSD=1.7), respectively. It was found that outdoor levels rather than indoor levels contributed significantly to personal exposure. The important exposure factors include the time spent outdoors and on transportation, riding a motorcycle, passing by factories, cooking or being in the kitchen, and incense burning at home. Motorcycle riding and the proximity to factories are related to the special living and housing characteristics in Taiwan, while incense burning and Chinese cooking are culture-related. Motorcyclists experienced an average of 27.7 microg/m(3) higher PM(10) than others, while subjects passing by a factory were exposed to an average of 38.4 microg/m(3) higher PM(10) than others. Effective control and public education should be applied to reduce the contribution of these PM exposure sources.