A thick layer of smog hovered over the northeastern Chinese city of Harbin for a third day, forcing the cancellation of many flights and even the closure of some main highways.
Though the situation in the city of 10 million has improved slightly since Monday, the pollution level is still about 15 times higher than what is considered safe by the World Health Organization.
On Tuesday, many schools and offices remained closed. Most flights were either delayed or canceled. State media said the pollution was so thick early on Tuesday that all of the city's highways were forced to close.
The official Xinhua news agency blamed the emergency on the first day of the public heating system being turned on in the city as winter approaches. State broadcaster CCTV claims the smog is expected to lift later Tuesday.
Pollution from rapid development and heavy coal use plagues many parts of China, prompting pledges from the country's leadership to make improvements. The government has promised for years to tackle the pollution problem, but has made little progress.