The smog blanketing the Chinese capital forced authorities at Beijing's international airport to cancel a score of flights on Wednesday.
Flights bound for Russia, Singapore and the United States were among those grounded due to poor visibility, terminal managers said on the airport's Web site.
Monitors installed at the U.S. Embassy in Beijing registered an air-quality reading of 430 at 1:00 p.m. Wednesday. A reading of 500 indicates maximum danger.
The monitors also detected a concentration of tiny particulates - dangerous because they can enter the lungs or bloodstream - of 395 micrograms per cubic meter of air, 15 times the level deemed acceptable by the World Health Organization.
Visibility in Beijing was less than 100 meters (327 feet) on Wednesday, according to the municipal weather service.
The smog may begin to lighten Wednesday night as the winds increase, Chinese government forecasters said.
The capital suffered its worst air quality on record during the period Jan. 10-16.
Beijing's acting mayor, Wang Anshun, announced Tuesday a series of pollution-reduction measures, including a program to get older vehicles off the roads.
Scientists say, however, that much of the pollution affecting the capital is generated by heavy industry in neighboring provinces. EFE