Why does Tehran experience severe air pollution?

Tehran experiences severe air pollution primarily due to a combination of human activity and geographic constraints. Emissions from motor vehicles, household fuel consumption, and a high concentration of industries generate significant atmospheric pollutants.1

These pollutants are exacerbated by the city's unique topography. The surrounding Alborz Mountains act as a barrier that prevents the dispersal of contaminated air. For approximately two-thirds of the year, pollutants are trapped beneath a dome of hot air, a condition worsened by limited precipitation and insufficient wind speeds to clear the atmosphere. Furthermore, prevailing winds from the west, south, and southeast often transport additional pollution from industrial areas into the city.12