A Comprehensive study on the effects of urban vegetation configuration on PM2.5 and outdoor thermal comfort

Despite the process of urbanization accelerating, the outdoor environmental quality is gradually declining. Greenery is generally considered an effective measure for improving environmental quality, it not only can reduce the dispersion and deposition of pollutants in the environment but can improve the outdoor thermal environment in the summer by regulating microclimate. The goal of our work is to optimize the types and layout of vegetation in specific spaces to maximize the creation of comfortable and safe outdoor environments. In our work, we selected a densely populated typical residential area in Jinan city and used ENVI-met software to simulate the impact of different vegetation configurations on pollutants and microclimate. According to the simulation results, we found that altering the canopy shape, vegetation type, tree spacing, and leaf area density (LAD) of vegetation have significant impacts on air quality and outdoor thermal environment, even exhibiting conflicting factors. Based on the comprehensive analysis, we suggested that planting trees on the outer row and shrubs on the inner row, and in this way, the reduction efficiency of PM2.5 was 65.34%, and the physiological equivalent temperature (PET) decreased by 8.24 °C, which achieved the better performance. The research will provide important recommendations for urban planners, contributing to promoting sustainable urban development and improving the physical and mental health of urban residents.