Investigation of PM2.5 Dispersion in Din Daeng District, Bangkok, Using Computational Fluid Dynamics Modeling

Abstract

Din Daeng is a small and densely populated district of Bangkok, with two major expressways and three main roads in the area. PM2.5 concentration in Din Daeng district often exceeds both the daily and annual standards of the National Ambient Air Quality Standards. Computational Fluid Dynamics (CFD) was applied to investigate the effects of the metropolitan characteristics and traffic volumes on the dispersion of PM2.5. The turbulent flow was analysed using the Standard k-ε model. There were two scenarios in this simulation study. One was to investigate the consequences of having the expressways. The other was to examine the influence of the city lockdown due to the COVID-19 pandemic. The presence of the expressways in Din Daeng district was demonstrated to increase PM2.5 concentrations by approximately 3.4 times compared to the case without the expressways. In addition, the city lockdown substantially reduced PM2.5 concentration by almost 49% compared to that during the normal period.