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Background and purpose: 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 PM2.5 in different transportation modes and factors that cause high indoor PM2.5 levels.
Materials and Methods: In this study, a calibrated real time monitor (MicroDust Pro) was used to measure PM2.5 levels in 3 mode of transportation (bus, car and train) on the same route. Results were also compared with PM10 concentrations measured by fixed site monitors. A small Poly Urethane Foam (PFU) filter was designed for PM2.5 size fraction monitoring and a small personal sampling pump was used to provide a continuous airflow through the gravimetric adaptor and photo detector.
Results: The mean PM2.5 concentration measured in the train was lower than the mean fixed site PM10 concentration. However, the mean PM2.5 levels in car and bus were much higher than those mean PM10 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 PM2.5 concentrations. However, stopping at the traffic light was the most important factor associated with peak PM2.5 concentrations inside the car.
Conclusion: 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.

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Background and purpose: High concentrations of respirable particles may cause high incidence of respiratory diseases and mortality in public populations and in particular in public transportation workers. Epidemiological exposure studies showed that respirable particles that emitted from traffic sources have more potential effects on more incidence of hospitalization or mortality caused by cardiovascular diseases. In this study personal exposures of bus drivers to respirable particles (PM10) and factors that caused high personal exposure were studied in Sari city.
Materials and Methods:In this study, a calibrated real time monitor (MicroDust Pro) with a personal sampling pump with 2 lit/min flow rate were used to measure Sari’s bus drivers personal exposure to PM10 concentrations on 3 main routs. This study was carried out during a one calendar year and all possible effective factors on personal exposure were recorded in a questionnaire.
Results:The mean personal exposures to PM10 concentrations among bus drivers were varied in different months. Exposure to PM10 concentrations were higher in autumn and winter and increased to 300µgm-3 in some days. Personal exposures to these particles were increased in the evening and on high traffic flow routs. Other factors such as rainy weather and temperature, number of passengers, bus' model year, picking up and dropping off the passengers were the most effectiveg factors on driver's personal exposures.
Conclusion:Bus drivers' exposure to respirable particles PM10 in Sari was varied in different time. It was due to entrance of outdoor particulate air pollutants into the bus during the picking up and getting off the passengers and resuspension of settled fine particles.