Update | Life grinds to a halt as dense smog descends on northern Chinese cities

Dense, choking smog blanketed several northern cities yesterday, with visibility in some areas reduced to less than 10 metres. Drivers complained they were unable to see traffic lights.

Air pollution in Harbin, capital of Heilongjiang province, rose above the highest point on the government's index for the second consecutive day. The city was forced to take the unprecedented step of closing kindergartens, primary and middle schools because of the smog.

In nearby Jilin province, Changchun and Jilin also suffered severe air pollution. Most of the province's main highways were closed.

Readings at several monitoring stations in Harbin showed concentrations of PM2.5, pollutants smaller than 2.5 microns across and considered a serious health hazard, had reached 1,000 micrograms per cubic metre in the afternoon - 40 times the safety level recommended by the World Health Organisation.

"The choking air smells pungent, hurting my eyes and nose," one resident wrote on Sina Weibo.

Others posted photos showing the city's high-rises disappearing into the smog.

The city's meteorological department issued a red alert for pollution in the morning, as visibility fell to less than 10 metres in downtown areas.