‘As the chart above shows, the cities with the worst air are often not big capitals, but provincial places with heavy industry in them or nearby. Ahwaz, for instance, in southwestern Iran, far outstrips infamously polluted cities like New Delhi or Beijing, with 372 parts per million of particles smaller than 10 micrometers (PM10), compared to the world average of 71. Life expectancy for the city of 1.2 million residents is the lowest in Iran.’ (Quartz).