The effect of the morphology of highly polluted urban areas neighborhood on suspended particles of PM 2.5 and PM 10 air pollutants (Case Study: Ahvaz, Iran)

• improper design of building forms can increase the amount of suspended. • research was conducted to identify the best building forms to reduce air pollutants. • each building form shows different reactions to changes in height, occupation level, and orientation. • The results can be used as a guide in designing effective building forms to reduce air pollution. Air pollution is one of the serious environmental challenges in large and industrial cities, which has direct and indirect consequences on human health and the environment. In many large cities, improper design of building forms can increase the amount of suspended particles. With population growth and urban development, managing and reducing air pollution has become essential. This study was conducted to improve indoor air quality and reduce the infiltration of atmospheric pollutants into residential spaces, utilizing the ENVI-met software as a computational fluid dynamics (CFD)-based simulation tool. This tool enables the analysis of the impact of architectural form on climatic conditions in urban environments. For this purpose, the concentration of PM2.5 and PM10 pollutants as the main criteria of air pollution in Ahvaz city was collected from the Environment and Protection Organization, and using detailed simulations, the effect of different building forms, including square forms, central courtyard, l-shaped, T-shaped, U-shaped, linear and Plus-shaped have been investigated. Design variables such as height, occupation level, and orientation of the building were selected as critical parameters and modeled at three height levels and different percentages of occupation level, which finally led to the production of 63 simulation scenarios. The results showed that the U-shaped form with a height of 16 meters, an occupation level of 60 %, and an orientation towards the east (Leeward) shows the best performance in reducing the penetration of PM2.5 and PM10. Compared to the current situation, the proposed model demonstrated improved performance, achieving a 23.40 % reduction in pollutants compared to Lashkarabad , 13.32 % compared to Shahrek Naft , 12.3 % compared to Zeytoon Karmandi , and 27.3 % compared to Koye Ostadan , proving its effectiveness in enhancing air quality. The findings of this study demonstrate that selecting building forms with consideration of pollutant types and environmental conditions plays a significant role in reducing air pollution levels. Simulation as an analytical tool in the early design phase enables a more precise assessment of the impact of various architectural forms and can serve as an effective approach in the sustainable design process. The results assist designers in identifying optimal options and can be used as a scientific reference by policymakers and urban planners to improve urban environmental quality.