City dwellers’ personal exposure to PM is influenced by numerous daily activities in multiple indoor and outdoor micro-environments (MEs). This study was designed to assess integrated personal exposure to PM across urban MEs together with the recording of individual time-activity patterns. We characterized simultaneously the personal exposure to PM2.5, black carbon (BC) and ultrafine particles (UFPs) in the Central Business District (CBD) area of Singapore. In addition, we quantified the Lung Deposited Surface Area (LDSA) concentration, which is an indicator of potential health impacts of UFPs. The field study was conducted over a 7-km walking route to identify air pollution hotspots. Subsequently, the personal exposure to PM2.5, BC and UFPs was measured at five selected hotspots for a duration of 1 hour, and across indoor and outdoor MEs under diverse daily human activities for 24 hours. The PM concentrations were found to vary considerably in both space and time at the CBD area. During the 1-hour personal exposure measurement, extremely high concentrations of PM2.5 (215 ± 129.5 µg m-3 and 36.4 ± 12.5 µg m-3) and BC (20.9 ± 10.4 µg m-3 and 18.1± 12.0 µg m-3) were observed at a temple and at a bus stop while elevated number concentrations of UFPs (320.8 ± 131.1 x 103 # cm-3) and LDSA (564.6 ± 276.5 µg2 cm-3) were measured at a food court. Potential health risk was estimated, which suggests that the continued inhalation of elevated levels of PM2.5 emitted from combustion sources is likely to lead to long-term adverse health effects among the exposed individuals. Overall, we provide insights into an individual's total exposure to PM based on time-activity patterns. The outcome of this work provides a scientific basis for development of air pollution control measures to mitigate personal exposure to PM at the city scale.