ABSTRACT
High concentrations of respirable particles may cause high incidence of respiratory diseases and mortality. Epidemiological exposure assessment is based on fixed site measurements in ambient air. However, major studies reported good relationship between indoor fine particulate air concentrations and personal exposure. This study is focussed on personal exposure to PM[2.5] in different transportation modes and factors that cause high indoor PM[2.5] levels. In this study, a calibrated real time monitor [MicroDust Pro] was used to measure PM[2.5] levels in 3 mode of transportation [bus, car and train] on the same route. Results were also compared with PM[10] concentrations measured by fixed site monitors. A small Poly Urethane Foam [PFU] filter was designed for PM[2.5] size fraction monitoring and a small personal sampling pump was used to provide a continuous airflow through the gravimetric adaptor and photo detector. The mean PM[2.5] concentration measured in the train was lower than the mean fixed site PM[10] concentration. However, the mean PM[2.5] levels in car and bus were much higher than those mean PM[10] concentrations measured by fixed site monitors. Boarding, picking up, dropping off, and movement of passengers inside the bus and train were significantly related to short-term increases in PM[2.5] concentrations. However, stopping at the traffic light was the most important factor associated with peak PM[2.5] concentrations inside the car. Penetration of particles that were created by road traffic and resuspension of fine particles in the vehicles were the most important factors that may increase respirable particles in transportation modes