Research on Optimization of Urban Commercial District Layout Based on PM2.5 Diffusion Simulation

Atmospheric particulate matter (PM) pollution has escalated into a critical threat to urban public health and safety. Among urban functional zones, commercial districts—characterized by high human exposure—are simultaneously hotspots of pollutant accumulation. Consequently, PM mitigation in these areas has become an urgent challenge for sustainable urbanization. This study used Computational Fluid Dynamics (CFD) to simulate the diffusion process and vertical concentration distribution of particulate matter in commercial districts. The results showed that the concentration of PM2.5 decreased with increasing height, with the highest concentration in the respiratory zone (1.5 m) and basic diffusion above 50 m; There are significant differences in the concentration changes of pollutants under different combinations of architectural spaces. By establishing a 20 m block wind corridor, changing the relationship between the building and the street enclosure, and adjusting the form of the building podium and overhead design with building height multiples (6–12 m), strategies can effectively alleviate the accumulation of particulate matter in commercial blocks. These findings provide quantitative evidence for evidence-based retrofitting strategies aimed at reducing PM2.5 exposure in high-density commercial areas.