Air pollution has killed 3,600 people in just a month in the Iranian capital Tehran, an official said Tuesday, describing the city's environmental situation as a "collective suicide". "Pollution has directly or indirectly caused the deaths of 3,600 people in the month of Aban (October 23 to November 23)," said Mohammad Hadi Heydarzadeh, director of Tehran's clean air committee, quoted by Kargozaran newspaper.