TEHRAN (Reuters) - Iranian authorities suspended a study in Tehran on Saturday for the second time this month due to high levels of air pollution, with low air stability that led to the formation of clouds in the sky of the city.

All universities, schools and kindergartens have been closed, the official IRNA news agency said, with the capital expected to see a higher level of air pollution today than in the past few days.

An Iranian website quoted Mohammad Taqizadeh, deputy governor of Tehran, as saying that the decision to disrupt the study was taken by a special committee in light of the high levels of air pollution in the city, which has more than nine million inhabitants.

For his part, Fars News Agency quoted Taqizadeh calling on the people of Tehran, especially the elderly and children, not to leave their homes except in case of extreme necessity, and the use of public transport.

In addition to disrupting the study, the authorities also decided to ban the entry of trucks and heavy vehicles into Tehran today, postponing sports competitions, and the measures taken included industrial cities.

In a statement carried by Fars, a spokeswoman for Tehran Air Quality Control Company said that the air pollution index in the capital is currently 142 micrograms per meter, explaining that in this case the air is unhealthy for those with health problems.

The study was suspended in Tehran on November 13 for the same reason, and ranks Tehran among the 12 highest polluted cities in the world.

According to data reported earlier this year by the Iranian news agency, quoting an official in the Ministry of Health, pollution causes the death of about 30 thousand people in Iran annually.