Air pollution in the Iranian capital, Tehran, has reached an alarming level, prompting authorities to shut down schools.
Hassan Karimi, a deputy of the governor general of Tehran, said on Saturday that all schools will be closed on Sunday in the capital.
He added that further decisions will be made on whether to close schools on Monday if the pollution continues in next days.
The megacity of Tehran, with an estimated population of 14 million people, is shrouded in a thick grey blanket of smog, suffering low visibility.
Emergency services are on full alert and residents, especially those with cardiac and respiratory problems and pregnant women, have been highly advised to remain indoors.
Officials have ordered polluting industries around the metropolis to turn off their machines for a whole week.
Traffic will be limited and smoke-belching cars will be fined or towed away as well.
The Air Quality Index (AQI) on Saturday showed a "red status" warning indicating that the air is unhealthy.
According to Iran’s Meteorological Organization, the air pollution will increase in Tehran in the next few days.
Eighty percent of Tehran’s pollution is blamed on exhaust fumes emitted from five million cars.