Once again heavy air pollution has clouded Tehran and other Iranian major cities; Officials say most of the pollution comes from vehicles on the congested roads of the rapidly growing metropolis of more than 13.5 million people, with a level of pollutants far exceeding World Health Organization standards. Each year, the 5.5 million vehicles in the city pump an estimated 5 million tons of CO2 into the air.
Among steps to try to reduce the pollution, Iran is converting heating systems in residential and commercial buildings to natural gas. Authorities are also expanding public transport, requiring vehicle emission inspections and developing more green spaces. But still air pollution is here;