Particle number and size distributions along the vehicular exhaust plume from a light-duty diesel vehicle

The characteristics of particle number and size distributions ranging from 15 nm to 30 μm along the vehicular exhaust plume emitted from a light-duty diesel vehicle under the low and high idling conditions were examined. The sampled exhaust particles were analyzed using the scanning mobility particle sizer (SMPS) and the aerodynamic particle sizer (APS) along the centerline of vehicular exhaust plume and under the environmental background. The results showed that the total particle number concentrations emitted from the tested diesel vehicle at high idling condition were much higher than those at low idling condition. However, the total particle number concentrations for both of idling conditions decreased with the distance departing from the exit port due to the deposition process. The results also indicated that most of particles from diesel vehicle were the fine particles less than 700 nm in diameter, and those particles would suspend longer time in the atmosphere than the large particles, resulting in the local particulate pollution.