EDITORS' NOTE: Reuters and other foreign media are subject to Iranian restrictions on their ability to film or take pictures in Tehran. Motorists travel on a highway in Tehran as the city is covered in dust July 6, 2009. The government closed private educational centres, state offices, industrial units and military bases for two days and raised its pollution alert status due to the dust, which an official from Tehran's environment office attributed the source to dust from dried marshland in Iraq blown towards Iran, according to the Iranian Mahr News Agency on Monday. REUTERS/Morteza Nikoubazl (IRAN ENVIRONMENT TRANSPORT)