Many parts of China have been engulfed by thick polluted smog for the second time in around two weeks.

According to Chinese reports, visibility was lower than 1,000 metres in the capital city, Beijing and a few other provinces. This has led to more people in hospital with respiratory illnesses and has prompted city Governments to warn residents to stay indoors.

Workers in some offices are believed to have worn protective headgear at their desks and pictures show the public walking in protective masks. State media also showed vehicles using full headlights in the morning to light their way through the smog and more than 100 flights are reported to have been cancelled due to poor visibility.

Reports claim the US Embassy reported a peak level of PM2.5, believed to be one of the worst pollutants, at 526 micrograms per cubic metre, or “beyond index” and more than 20 times higher than World Health Organisation safety levels over a 24-hour period.

Beijing’s acting mayor said the city would strengthen its efforts to treat PM2.5 and cut the density of major air pollutants by 2% this year. The capital aims to take 180,000 old vehicles off the road and promote clean energy cars among Government departments, the public and cleaning sectors. He also said heating systems of 44,000 old homes will be replaced, with the aim of speeding up the promotion of clean energy in rural areas.

The city also aims to cut coal usage by 1.4 million tonnes and other volatile compound emissions by 8,000 tonnes as well as close around 450 heavily polluting plants.