TEHRAN (AP) – For the second time in a month, heavy air pollution in the smog-filled capital has forced authorities to close government offices and schools and declare a two-day public holiday because of the health dangers of being outdoors.

A government committee decided pollution levels in Tehran warranted the closure of all government offices, schools and industries on Wednesday and Thursday because of “polluted and unhealthy” conditions.
Critics say each holiday incurs about $130 million in financial losses.
The air over Iran's capital is among the most polluted in the world, and health experts say many Iranians suffer serious health problems as a result.
Most of the pollution comes from vehicles on the congested roads of the rapidly growing metropolis of more than 12 million people, and the level of pollutants far exceeds World Health Organization standards. Each year, the 1.4 million vehicles in the city pump an estimated 5 million tons of CO2 into the air, according to the Tehran mayor's office.
Tehran has a similar geographical position to Los Angeles and Mexico City -- two other cities that experience heavy air pollution.
The mountains ringing the capital on three sides and the warm air rising from the other help to trap the pollution, and there is little wind to clear it.
Frequent sunshine and temperature inversions also help transform pollutants into ozone and other poisonous smog.
Among steps to try to reduce the pollution, Iran is converting heating systems in residential and commercial buildings to natural gas. Authorities are also expanding public transport, requiring vehicle emission inspections and developing more green spaces.