Air pollution readings soared on Thursday in Chinese capital of Beijing where residents were warned to take precautions.
Thursday’s readings registered more than 20 times the recommended exposure levels by the World Health Organisation (WHO).
WHO guidelines say average concentrations of the tiniest pollution particles – called PM2.5 – should be no more than 25 microgrammes per cubic metre.
On Thursday, official readings for PM2.5 at one point showed more than 500 microgrammes per cubic metre.
Thick smog reduced visibility to a few hundred metres, blanketing skyscrapers and leaving a sour smell in the air.
Officials advised people going to work to wear protective masks, and children and the elderly to stay indoors.
Four highways linking Beijing to other cities were temporarily closed on Thursday morning due to poor visibility, Chinese state news agency said.
China’s cities are frequently blanketed by pollution caused by coal-burning power plants, factories, and millions of vehicles on the roads. Estimates show that air pollution causes hundreds of thousands of premature deaths every year.
