Chinese lose patience with pollution

"Increasing air pollution might be largely to blame," said Zhi Xiuyi, director of the lung cancer treatment unit at Capital Medical university, to the newspaper.

In the panic over the smog, Chinese retailers reported a jump in sales of protective masks, with 30,000 being sold on Sunday alone.

As commuters in Beijing turned on their fog lights and lost sight of the tops of their buildings, the city's Municipal Environmental Protection Bureau stuck to its line that air pollution was merely "moderate" only to be greeted with scorn.

"The city is claiming the smog has not reached 'medium pollution'. It is like being stabbed in the chest, without it piercing the heart, and claiming it as a 'minor' injury," said one commenter on Weibo, China's version of Twitter.

By contrast, the monitor of the roof of the US embassy, which broadcasts its readings automatically on the internet, went off the chart on Sunday, registering a measurement of "beyond index".

"The air has got worse and worse for a month, and this so-called 'fog' has lasted for days. Many people do not dare step outside. Masks have sold out. Our health is in danger. Many people are asking themselves whether they should stay in Beijing or leave," said another.

Ma Jun, the head of one of China's few environmental NGOs, the Institute of Public and Environmental Affairs, said the pollution across the North East was a combination of unfortunate weather and a haze of suspended particles from coal fires and industrial smoke stacks.

"Because particle pollution has reached an alarming level, any unfavourable weather, such as the current lull in wind, can cause quite serious consequences," he said.

"The government has made some efforts, for example switching to gas instead of coal in city centres. But there has been a huge rise in the number of cars, and large industrial parks now surround Beijing, which can still blow pollution over the city."

Mr Ma said the government should release transparent and accurate pollution readings so that the public could take its own precautions.

In the longer term, he urged a greater public transport programme and emissions controls on industry.

"People are more environmentally aware, and they are angry at the lack of transparency from the government," he said.

In the past two years, Beijing officials have announced good or excellent air quality nearly 80 per cent of the time. But the US embassy monitor, a source of some diplomatic tension, has flatly contradicted the official line. From January 2010 to last October, Beijing has only had 13 days a year of "good" air, and 297 days a year of unhealthy to hazardous air.

To achieve the official readings, Beijing has rearranged its monitoring stations twice since 2006, and takes an average across several stations, including one in the countryside that is some 20 miles outside the city centre. Beijing officials have now bowed to public pressure and said they will begin to provide readings of fine particulate pollution, the most damaging to human health, but only in 2016.