City authorities issued a rare orange alert, the second highest of four danger levels. Schools suspended outdoor activities and polluting factories were required to reduce production.
Visibility was cut to several hundred metres, as buildings receded into thick smog. People complained of a smoky, pungent odour, and many wore tight-fitting face masks.
“I felt like my lungs were blocked,” said Xu Pengfei, a security guard at an office building in downtown Beijing. “We have to stand in the open for many hours a day, and the pollution really affects us.”
The city said the levels of hazardous tiny PM2.5 particles in the air exceeded 600 micrograms per cubic metre at several monitoring sites late yesterday afternoon. The US Embassy in Beijing reported 666 micrograms per cubic metre in the evening.
Outside Beijing, the readings were as high as 976 micrograms in the suburban region of Liulihe. The World Health Organisation considers the safe level of PM2.5 particles to be 25 micrograms per cubic metre on a 24-hour average basis.
Beijing has vowed to clean up its notoriously foul air and had been doing fairly well this year, with generally cleaner air than in 2014.
But the city was hit by unusually cold days and early snow in November, and winter heating was turned on. For the entire month, the capital saw hardly any blue skies and was shrouded in persistent smog.