Impact of Non-Exhaust Emission on Ambient Particulate Matter Concentration using a Coupled Atmospheric Chemistry –CFD Model

Vehicular emissions are major sources of gaseous and particulate matter pollutants in urban atmospheres. Stringent environmental regulations on vehicular emissions have been consistently implemented, leading to a substantial decrease in exhaust emissions. In contrast, non-exhaust emissions are increasing with the growing share of electric vehicles. Non-exhaust particulate matter emissions account for approximately 90% of total vehicular emissions. However, standardized guidelines for non-exhaust emissions have not been established, largely due to the challenges in estimating ambient concentrations from non-exhaust particulate matter sources. In this study, we performed a particulate matter simulation to investigate the quantitative impact of non-exhaust emissions in Seoul, using a coupled atmospheric chemistry–CFD model (CFD-Chem). We evaluated the model using various emission factors and determined the most accurate emission factor by comparing it with observed PM concentrations at the pedestrian level. Our simulated PM concentrations follow the diurnal variation of traffic volume, indicating a significant contribution of non-vehicular emissions to PM concentration at ground level. We observed that the impact of non-exhaust sources on pedestrians is higher in alleys than on main streets. Our results suggest that precise simulations are essential for establishing accurate and standardized guidelines for non-exhaust emissions.