Air pollution forced the closure of schools and universities in several parts of Iran on Saturday, including Tehran, which was cloaked by a cloud of toxic smog.
The decision to shut schools and universities in the capital was announced late on Friday by deputy governor Mohammad Taghizadeh, after a meeting of an emergency committee for air pollution.
"Due to increased air pollution, kindergartens, preschools and schools, universities and higher education institutes of Tehran province will be closed," the state news agency Irna quoted the deputy governor as saying.
An odd-even traffic scheme was imposed to restrict the number of private vehicles on roads of the capital city and trucks were banned outright in Tehran province, Irna reported.
The young and elderly and people with respiratory illnesses were warned to stay indoors and sporting activities were suspended on Saturday, the start of the working week in Iran.
Schools were also closed in the northern province of Alborz and in the central province of Isfahan, Irna reported.
Other areas where schools were shut included the north-eastern city of Mashhad, Orumiyeh city in north-western Iran and Qom, south of Tehran.
In Tehran, average concentrations of hazardous airborne particles reached 146 micrograms per cubic metre on Saturday, according to air.tehran.ir, a government-linked website.
The pall of pollution has shrouded the sprawling city of eight million for days and is only expected to dissipate on Monday, when rain is forecast.
Air pollution was the cause of nearly 30,000 deaths per year in Iranian cities, state media reported earlier this year, citing a health ministry official.
The problem worsens in Tehran during winter, when a lack of wind and the cold air traps hazardous smog over the city for days on end – a phenomenon known as thermal inversion.
Most of the city's pollution is caused by heavy duty vehicles, motorbikes, refineries and power plants, according to a World Bank report released last year.
