Smog thickens again in Beijing with pollution at danger levels

Air pollution spiked to dangerous levels again in Beijing yesterday, with skyscrapers vanishing amid the acrid smog and facial masks becoming so common they look like a new fashion trend.

Local weather authorities issued yellow alerts for both fog and smog - the third-highest level on a four-tier colour-coded warning system - indicating that visibility could drop below 500 metres, Xinhua reported.

It reported that the southern part of the capital was likely to see the densest smog, while visibility across most of the city remained below 3,000 metres.

By 4pm, the air pollution index in central Beijing exceeded 300, which the government rates as "hazardous", and an air monitoring station near a flyover in the Xicheng district recorded a level of 423.

A "hazardous" level over a 24-hour period is considered bad enough to make even healthy people ill.

Neighbouring cities also saw heavy smog. In Shijiazhuang , Hebei , the air pollution index exceeded 500.

Provincial authorities had to shut down several airports and nearly all highways as visibility dropped to less than 50 metres in nearly 20 cities and counties, according to China News Service.