Smog levels in northern China – in pictures

A man pushes a bike onto a bridge in Harbin Photograph: AP

A woman wearing a mask checks her phone in front of Harbin's landmark San Sophia church. The second day of heavy smog has forced the closure of schools and highways, as visibility has been reduced to a few metres Photograph: Reuters

Two women share a jacket to cover up their mouths and noses as they cross a street covered by dense smog. Small-particle pollution soared to a record 40 times higher than an international safety standard Photograph: AP

A traffic policeman signals to drivers. Local media have linked the pollution in Harbin to the city switching on its public heating system for winter Photograph: China Daily/Reuters

People wear masks as they ride along a street in Daqing, Heilongjiang province. All of the province's highways and the Taiping international airport in Harbin have been forced to close Photograph: Reuters

A woman wears a mask as she takes part in communal dancing. An index measuring PM2.5, or particulate matter with a diameter of 2.5 micrometres in the air, reached a reading of 1,000 in some parts of Harbin. World Health Organization guidelines say average daily concentrations should be no more than 25 microgrammes per cubic metre Photograph: AP

Smog shrouds buildings in Harbin. A red alert for thick smog has been issued in the provinces of Heilongjiang, Jilin and Liaoning Photograph: Rex Features

People wait for transport in Harbin but many public bus routes were shut due to the smog Photograph: Rex Features

A man covers his nose and mouth with a newspaper as he walks on the street in Harbin Photograph: AP

A statue of Chairman Mao is seen through the smog in Shenyang, Liaoning province Photograph: Sheng Li/Reuters