Authorities in Tehran have closed schools on November 14 because of dangerous levels of pollution in the atmosphere.
"Kindergartens and primary schools are closed on Monday [November 14] in Tehran and most of the cities of the province," the Education Ministry said, according to official IRNA agency.
A blanket of smog descended on the Iranian capital on November 13, leading many of its 14 million residents to stay indoors or wear masks in the street.
Officials extended restrictions on traffic in parts of the city and deployed ambulances to wait on standby in the busiest and dirtiest areas.
The pollution is expected to continue until November 16 when forecasters hope winds will move the stagnant air, an official told state television.
Tehran is among the most polluted capital cities in the world.