Various factors affect the pollutant entering the buildings. One of which is the buildings form and its various components configuration. In this regards, balconies are one of the external components of the buildings, which play a significant role in pollutant entry to the buildings. Until now, various researches have been investigated the role of balconies on the pollutant exposure in the street canyons. While, this issue has not been investigated in relation to indoor spaces so far. Based on, this research investigates the role of balcony configuration on the pollutant concentration inside the buildings. For this, 16 balcony forms in terms of geometry, depth, length, and parapet were simulated in CFD. The building is located near an urban highway (as a source of pollution). Introducing the best balcony configuration in which increases the inside ventilation and prevent the pollutant entering the building is one of this research goal. For this the TOPSIS method is used. In this research, NO₂ emissions have been investigated as one of the pollutant particles generated by vehicle traffic. The results show that the balcony with less spatial confinement significantly prevent the pollution entering the building and increase the indoor air quality (IAQ). This article can lead to a deeper understanding of the impact of buildings configuration specially balcony forms on the indoor air quality in the middle rise urban buildings.