Abstract: “This study aims to determine the in-vehicle and outdoor fine particle (PM2.5) concentration and particle number concentration (PNC) for six size ranges (0.3-0.5 μm, >0.5-1.0 μm, >1.0-3.0 μm, >3.0-5.0 μm, >5.0-10 μm, and >10 μm). The measurement campaign was conducted in the morning and evening onboard the Metrobus, red-bus and outdoors. PM2.5 concentration in the Metrobus and red bus were observed as 58.8±10.2 μg/m3 and 76.2±30.9 μg/m3 respectively, and the outdoor value was about 2 times more. For both types of public transportation, the ratio of the amount of internal environment PM and the amount of external environment PM displayed a high level of correlation (redbus/ outdoors, R=0.97; Metrobus/outdoors, R=0.88) with the PM size. The number of commuters, vehicle ventilation type and outdoor air entering the vehicles probably caused the differences in in-vehicle particle concentrations.”

Keywords: public transportation, air quality, PM2.5, particle number concentration