Beijing residents were warned Monday to stay indoors due to high pollution levels, as a blanket of heavy smog across northern China caused traffic chaos and delayed flights throughout the region. "Under these weather conditions it is better to reduce outdoor activities especially in areas where pollutants are concentrated such as where traffic is heavy," the Beijing environmental protection bureau said on its website.
"Residents should take measures to protect themselves in order not to breathe heavily polluted air." During the 24-hour period from Sunday noon, Beijing's air quality was rated a "hazardous" four on a scale of five, the bureau said, with five representing the worst level of pollution.
Besides the regular car pollution, the bad air quality was also due to the city's 6,000 coal-fire heating furnaces and up to two million home coal burners that went into operation this month to provide the capital with heat, it said.
Meanwhile the blanket of smog caused traffic chaos as drivers were left lined up at numerous highways that were shut down due to the atmospheric conditions. Five highways in the capital and eight in neighboring Tianjin were shut down beginning late Sunday due to the fog, which reduced visibility in some places to as low as 10 meters (33 feet), Xinhua news agency reported.
EDIT
http://www.terradaily.com/reports/Beijingers_Told_To_Stay_Indoors_As_Smog_Hangs_Over_North_China_999.html