TEHRAN, Iran (AP) — Iran announced Tuesday that all governmental offices, universities, and schools in the province of Tehran will be closed for two days because of poor air quality, state TV reported.

The capital city of Tehran — home to over 10 million people — saw the closure of elementary schools and kindergartens on Saturday and Sunday, but authorities said Tuesday that because of increasing pollution, all governmental offices, universities and schools will be closed on Wednesday and Thursday, adding that schooling will continue on online platforms.

The TV report also said that banks, essential public services and health centers would remain open on those days.

Authorities also announced that schools and universities in neighboring Alborz province, and the central province of Isfahan will be closed on Wednesday and Thursday.

In Iran, schools usually work from Saturday to Wednesday.

On Tuesday visibility was low in Tehran, and authorities warned of poor air quality and advised the elderly, sick, and children to take extra precautions.

From time to time, authorities respond to the pollution with similar measures.

Tehran’s air quality is among the worst in the world. The smog is mostly caused by heavy traffic due to millions of fuel-burning cars, motorbikes and factory emissions. It worsens during the cold season because of a lack of wind and rain.

The city is surrounded by tall hills and mountains on three sides. Cold, stagnant air settles in the valley, trapping automotive and other emissions that cannot escape.

In July 2022, schools and government offices closed in Iran’s capital and several other cities in the country, after a sandstorm blanketed Tehran and the surrounding region.