Stocks of gas face masks as well as air purifiers have sold like hotcakes in China early this week as the Asian country fights and cleans off its worst yet smog pollution which hit large parts of Central and East China over the weekend. Such a price the country has to pay in exchange for global economic supremacy.

360buy.com and gome.com.cn, two of China's leading e-commerce sites, said most of its stocks of air purifiers have ran out on Monday, triggered by the presence of the unpleasant smoke and haze that enveloped large areas of the country over the weekend that lasted well into Monday.

Sales of face masks likewise have ran out.

"The purchases were made because of the pollution for sure," an unidentified manager of pharmacy chain Jinglongtang told AFP. "The masks were all sold out by Monday," she said.

With the frenzy over the smog, shares of Chinese face-mask manufacturer Shanghai Dragon jumped 10 per cent daily limit for the second consecutive day. Fujian Longking, a pollution control equipment maker, was likewise up 9.64 per cent in morning trading.

On Jan 12, official measures of PM2.5 rose to as high as 993 microgrammes per cubic meter in Beijing. The criteria set by the World Health Organisation that is considered humane and still safe is no more than 25.

PM2.5 are fine airborne particulates that pose the largest health risk. The Jan 12 levels, according to the Institute of Public and Environmental Affairs, were believed to be the highest for the city.

Because of the incident, Beijing was forced to implement its emergency response plan for hazardous pollution for the first time ever on Sunday, according to Yu Jianhua, director of the air quality department under the municipal environmental protection bureau.

Among those instituted in the plan were to limit construction activity, limit the use of government vehicles as well as discontinue outdoor activities for school-related events. The plan was issued in 2012.