All kindergartens, schools and universities were shut down in the Iranian capital city of Tehran as well as a number of other cities on Saturday as air pollution levels have risen to hazardous levels.

The decision was made a day earlier by the Air Pollution Exigency Committee, according to Tehran Province Deputy Governor Mohammad Taghiizade.

Taghiizade said that the odd-even traffic scheme will be applied all across the capital and that the ban on the movement of trucks as well as the activity of sand mines and concrete industries would remain in place.

He further extended the ban on holding outdoor sports matches until further notice.

Over the past few days, Tehran has been blanketed by heavy smug, with the air pollution reaching the level considered unsafe for all groups of people.

Authorities have urged citizens, especially children, pregnant women and the elderly, to stay indoors.

Kindergartens and schools were also shut down in Alborz Province near Tehran on Saturday.

All pre-school centers and primary schools were also closed in the northwestern city of Urmia and the central city of Isfahan.

The photo shows the smog-shrouded Milad Tower in Tehran on November 28, 2019. (By Tasnim news agency)

Each winter, Tehran, a metropolitan city surrounded by mountains, suffers some of the worst air pollution in the world through thermal inversion -- a phenomenon that traps hazardous air over the city.

Other industrial Iranian cities also experience similar periodic heavy air pollution.