One of northeastern China's largest cities, Harbin, home to 11 million people, was all but shut down due to worsening air quality. All primary and middle schools, the airport and many bus routes have been closed as the visibility in the city has been reduced to 10 meters.
According to Reuters: An index measuring PM2.5, or particulate matter with a diameter of 2.5 micrometers (PM2.5), reached a reading of 1,000 in some parts of Harbin,
the gritty capital of northeastern Heilongjiang province and home to some 11 million people.
A level above 300 is considered hazardous, while the World Health Organization recommends a daily level of no more than 20. The current spike is blamed on the city's heating being turned on for winter,
and is expected to clear within 24 hours.