Variation of PM_(2.5) concentrations in relation to street washing activities

摘要

Several studies conducted in urban areas have pointed out that road dust resuspension contributes significantly to PM concentration levels. Street washing is one of the methods proposed to reduce resuspended road dust contributions to ambient PM concentrations. As resuspended particles are mainly found in the coarse mode, published studies investigating the effects of street washing have focused on PM_(10) size fraction. As the PM_(2.5) mass fraction of particles originating from mechanical abrasion processes may still be significant we conducted a study in order to evaluate the effects of street washing on the mitigation of resuspension of fine particles. The PM_(2.5) mass concentration data were examined and integrated with the occurrence of street washing activities. In addition, the effect of the meteorological variability, traffic flow and street washing activities, on ambient PM_(2.5) levels was evaluated by means of a multivariate regression model. The results revealed that traffic flow is the most important factor that controls PM_(2.5) hourly concentrations while street washing activities did not influence fine particle mass levels.