Ahvaz (Persian: اهواز Ahvāz‎) is a city in the south of Iran. At the 2006 census, its population was 1,432,965, in 796,239 families. Ahvaz has the world's worst air pollution according to a survey by the World Health Organization in 2011.Ahvaz is built on the banks of the Karun River and is situated in the middle of Khūzestān Province. The city has an average elevation of 20 meters above sea level.