PM2.5 exposure is associated with short-term and chronic respiratory effects. Therefore, there is a need to investigate human exposure to PM2.5 inorder to support assessment of the association between exposure and adverse health effects. The methodology used in the current version of Stochastic Exposure and Dose Simulation Model for Particulate Matter (SHEDS-PM) for in-vehicle PM2.5 concentration is reviewed. An alternative approach of estimating in-vehicle PM2.5 concentration based on the use of a dispersion model to estimate near-road PM2.5 concentration and a mass balance model for estimating in-vehicle concentration has been specified and applied. Theobjectives of this paper are to: (a) demonstrate the application of the alternative approach to various scenarios; (b) analyze the sensitivity of the modeling results to the key inputs; and (c) evaluate this approach. Typical inputs for the alternative approach are reviewed. Sensitivities of these inputs to the modeling results and estimated human exposure have been analyzed. The in-vehicle PM2.5 concentration was estimated to vary by morethan a factor of two depending on factors such as the cabin air exchange rate and filter efficiency of the ventilation system. Recommendations aremade for field data that would be useful to better characterize variability in factors that affect in-vehicle PM2.5 concentration.
Abstract