BEIJING —Heavy smog in northern China on Sunday caused hundreds of flights to be canceled and highways to shut, disrupting the first day of the new year holiday.
Large parts of the north were hit by hazardous smog in mid-December, leading authorities to order hundreds of factories to close and to restrict motorists to cut emissions.
The latest round of air pollution began Friday and is expected to persist until Thursday, although it is expected to ease slightly Monday, the last day of the new year holiday.
Average concentrations of small breathable particles known as PM2.5 were higher than 500 micrograms per cubic meter in Beijing — 50 times higher than World Health Organization recommendations.
A total of 24 Chinese cities have issued red alerts for the current round of pollution, which mandate measures like limiting car usage and closing factories, while 21 have issued orange alerts, including Beijing and Tianjin.