Ahvaz in Iran tops WHO air pollution index
Ahvaz in south Iran is one of the world's most polluted cities, according to a recent air quality survey by the World Health Organization.
The city, with a population of about 1.2m people, had the highest count of small airborne particles out of 1,100 urban areas around the world.
These particles can cause asthma, heart disease and lung cancer, and the problem in Iran is made worse by dust storms.
Karen Zarindast reports.