This study investigates temporal variations in PM levels in Taipei bus terminal and assesses exposure levels for bus terminal workers. Measurement results show that temporal variations in PM levels in the waiting room and on the platform of this indoor bus terminal were strongly associated with bus traffic volume. The PM10, PM2.5, and ultrafine particle (UFP) levels on the bus platform were 1.9, 2.0, and 1.2 times higher than those inside the waiting room, respectively. Additionally, PM10 and PM2.5 levels on the platform were approximately 2.3 and 2.8 times higher than those at an ambient monitoring station, respectively. Measurement results indicate that the major PM source inside this bus terminal is diesel buses and that PM can be trapped in this semi-confined bus terminal to a far greater extent than in typical open-air bus stations. Daily PM exposure levels for station ticket inspectors who check passenger tickets in the waiting room and manage arriving and departing buses on the bus platform are assessed. Daily PM exposure levels for station ticket inspectors during different shifts are calculated based on average PM levels and working time spent in the waiting room and on the platform. Based on observational results, station ticket inspectors spend approximately 80–85% and 15–20% of their working time in the waiting room and on the platform, respectively. Daily PM10 and PM2.5 exposure levels for station ticket inspectors were approximately 1.3–1.5 and 1.6–1.8 times higher than those in the outdoor atmosphere, respectively. Additionally, daily UFP exposure levels for station ticket inspectors were approximately 5.6–7.2 times higher than those in the urban background. Measurement results demonstrate that potential health risk induced by PM is high for station ticket inspectors who work for long periods at this indoor bus terminal.