Young and old residents of the Chinese metropolis of Wuhan were advised to stay indoors on Monday after a thick haze blanketed the city of nine million people, official media said.
Described by residents as opaque with yellowish and greenish tinges, the fug descended suddenly in the morning, prompting people to rush to put on face masks, witnesses told AFP.
The official Xinhua news agency quoted the environmental protection department of Hubei province saying in a statement: “Children, the elderly and people with heart or respiratory diseases are advised to stay indoors.”
Xinhua said straw burning was the cause and denied there had been any industrial accidents in or near Wuhan, after Internet rumours suggested there had been an explosion at a chemical complex north-east of the city.
“I looked out of the window of my office and I could not believe my eyes,” said resident Li Yunzhong.
“At first I thought it was going to rain. In 31 years in Wuhan I have never known anything like it. We are very worried because we do not know what it is.”
France’s consulate-general in the central city advised residents to stay at home, close their windows and limit the use of air-conditioning.
“The source of the thick cloud that has covered the city of Wuhan since this morning is at present unknown,” it said on its website.