Extremely high pollution levels are shrouding eastern China for the second time in two weeks, forcing airlines in Beijing and elsewhere to cancel flights because of poor visibility and prompting government warnings for residents to stay indoors.
The outlines of buildings in the capital receded into a white mist as pedestrians donned face masks to guard against the thick, caustic air, which stranded passengers during the first week of the country's peak, six-week period for travel surrounding the Chinese New Year on February 10.
The US Embassy reported a peak level of PM2.5 - one of the worst pollutants - at 526 micrograms per cubic metre, or "beyond index", and more than 20 times higher than World Health Organisation safety levels over a 24-hour period.
Liu Peng, an employee at a financial institution in Beijing, said he would keep his newborn baby indoors.
"It's really bad for your health, obviously," he said. "I bike to work every day and always wear a mask. The pollution in recent years is probably due to the increase in private cars and government cars."
Beijing's official readings for PM2.5 were lower than the embassy's - 433 micrograms per cubic metre at one point - but even that level is considered "severe" and prompted the city government to advise residents to stay indoors as much as possible.
The government said that, because there was no wind, the smog would probably not dissipate quickly.
Visibility was less than 100 metres in some areas of eastern China, the official Xinhua News Agency reported. More than 100 flights were cancelled in the eastern city of Zhengzhou, 33 in Beijing, 20 in Qindao and 13 in Jinan.
Ren Haiqiang, a bank worker in his early 30s, said he had booked tickets to fly out of Beijing on Thursday to visit family in the coastal city of Dalian, but was now worried about flight cancellations.
"Traveling over the holiday is already a huge hassle, along with all the gift-giving and family visits. We thought flying would be the best way to avoid the crush, but if the weather continues like this we'll be in real trouble," he said as he queued at a bakery in Beijing.