BEIJING -- Thick, off-the-scale smog shrouded eastern China for the second time in about two weeks Tuesday, forcing airlines to cancel flights because of poor visibility and prompting Beijing to temporarily shut factories and curtail fleets of government cars.
The capital was a colorless scene. Street lamps and the outlines of buildings receded into a white haze as pedestrians donned face masks to guard against the caustic air. The flight cancellations stranded passengers during the first week of the country's peak, six-week period for travel surrounding the Chinese New Year on Feb. 10.

The U.S. Embassy reported an hourly peak level of PM2.5 - tiny particulate matter that can penetrate deep into the lungs - at 526 micrograms per cubic meter, or "beyond index," and more than 20 times higher than World Health Organization safety levels over a 24-hour period. http://www.wunderground.com/news/china-dangerous-smog-20130114