For the second straight day, smog has choked China's northeastern city of Harbin.
The city in Heilognjiang province all but shut down.
Schools and roads closed and flights were disrupted.
In some parts of the city visibility was reduced to 10 metres.
(SOUNDBITE) (Mandarin) DEPUTY CHIEF OF BEIJING MUNICIPAL ENVIRONMENTAL PROTECTION BUREAU FANG LI SAYING:
"Our emergency measures to tackle heavy air pollution include two major ways. The first is to immediately remind the public of taking useful protection measures to reduce harm to their health as much as possible. The second is to take strict measures to reduce pollutant emission and try our best to ease the severity of air pollution."
Media have linked the pollution to the city turning on its public heating system for winter.
The density of airborne particles soared above the World Health Organisation's recommended limits.
(SOUNDBITE) (Mandarin) 28-YEAR-OLD RESIDENT LI LI SAYING:
"So