Photos by Borna Ghasemi, ISNA

A severe dust storm hit the city of Ahvaz in Khouzestan province in southwestern Iran on Saturday causing health concerns for the residents. In recent years, dust storms have become a common thing for the western cities in Iran.

In September 2011, the World Health Organization (WHO) said Ahvaz is the world's most polluted city. According to a study by WHO, Ahvaz has the highest measured level of airborne particles small enough to cause serious health problems in humans. Ahvaz is a heavily-industrialized city known for oil fields.
 

 
Ahvaz, Iran