The Importance of Building Density in Reducing Air Pollution of Cities (Case Study: Arak City)

Iranian big cities suffer from air pollution which causes irreparable damage to the health of citizens. Airflow is a significant parameter in removing pollution from urban spaces and is largely affected by the physical shape of the buildings’ environment. Buildings’ height, density, and enclosure of open spaces are the physical factors that affect airflow of cities. In this research, first, the air pollution distribution map (carbon monoxide) of the city was calculated using Arc GIS software and then considering the different heights of buildings in Arak city, the function of air pollution indicators was analyzed. The results showed that an increase of the average air pollution to the building density coefficient in an area in Arak is equal to 0.013, which means increasing urban density reduces airflow in the environment and stabilizes air pollution. Moreover, there is a significant relationship between the average air pollution in the area and the percentage of the built mass volume. The coefficient obtained from this relationship is equal to 0.085, which indicates how this index affects air pollution. It turns out that the higher the mass-to-space ratio in a range, the greater the amount of pollution in the environment. Since the coefficient obtained for the percentage index of the mass volume is more than the coefficient of building density, it can be concluded that this index can play a more decisive role in an urban area.