Xie Nan, a hostess of Heilongjiang Television said on Weibo, "Two screens appear in the air at 9:00 am in Beijing. Take a closer look and it turns out that the Pangu building is being 'eaten up' by the smog." [Photo from Weibo]

Xie Nan, a hostess of Heilongjiang Television said on Weibo, "Two screens appear in the air at 9:00 am in Beijing. Take a closer look and it turns out that the Pangu building is being 'eaten up' by the smog."

A netizen with the name Xiaoyu Brother Designer said, "I could not find direction in the northern smog while you could not encounter snow in the southern sun."

Visitors walk at the Tian'anmen Square amid severe smog in Beijing on Tuesday. [Photo/IC]

The social networking site is also full of pictures of landmarks in Beijing disappearing in the smog. Sina News posted such pictures with a posting saying that "in the dense smog, all these landmarks in Beijing disappeared."

A weather forecast issued by Beijing Meteorological Bureau on 8 am of Tuesday shows that severe smog hit six major districts of Beijing. [Photo from Weibo account of Beijing Meteorological Bureau]

By 12 am of Tuesday, the concentration of PM2.5 - particulate matter with diameter of less than 2.5 microns that can penetrate the lungs and harm health - reached 611 micrograms per cubic meter in six major districts of Beijing, according to Beijing Municipal Environmental Monitoring Center.

Severe smog has lasted for five days in Beijing since Friday. At 10 am on Sunday, Beijing issued the first air pollution orange alert this year. As smog continues to aggravate, some monitoring stations in southern Beijing show the concentration of PM2.5 reached a peak of nearly 1,000 micrograms per cubic meter on Monday night. By 2 pm of Tuesday, the orange alert had lasted for more than 50 hours.