A person performs morning exercise in front of the barely visible Oriental Pearl TV Tower, which is shrouded by smog, in Shanghai on Friday. Photo: IC

China's eastern coastal region has been shrouded by the most severe smog yet this winter, which has led to a surge in sales of masks and air cleaning machines.

The National Meteorological Center Friday issued an orange alert for smog, the second most serious possible in China's four-tiered system, on its website. It forecasts severe smog for Jiangsu Province and Shanghai as well as parts of Zhejiang, Anhui and Hebei provinces. The situation is not expected to improve until a cold front clears the sky on Monday.

According to the Shanghai Environmental Monitoring Center, the city's air quality index reached 482 at 6 pm Friday, indicating severe pollution. And the reading for PM2.5 (particulate matter under 2.5 micrograms) soared to 602 at around 2 pm on Friday, over eight times the safe level of 75.

While Beijing enjoys a rare spate of clear weather and blue skies, Shanghai has been suffering from serious smog for a week. Many pedestrians and riders on the street wore masks on Friday to guard against the pollution.

A local resident surnamed Zhang told the Global Times that she had purchased masks for all her family since winter began. She is now planning to buy a 5,000 yuan air filter since the haze is getting worse.

Demand for masks is outstripping supply in eastern China and sales of air cleaning machines in the second half of November surged, showing an increase of 680 percent year on year, according to a Xinhua News Agency report on Friday.

Shanghai municipal government launched a series of measures in response to the smog including shutting down major industrial plants and suspending major outdoor activities as well as banning 30 percent of government vehicles from the roads on Friday.

"The number of patients in recent days has surged 50 percent compared to the same period last year. Although it cannot be confirmed that the smog is causing respiratory diseases now, it's certainly the case that the weather is hitting people's health," a doctor, who asked not to be named from Shanghai No.9 Hospital, said.