Photo taken on Dec 23, 2015 shows Donggang CBD in smog in Dalian, Northeast China's Liaoning province. [Photo/Xinhua]

Smog depresses the northern cities

Several alerts of smog attacks during the winter destroyed the general impression that air pollution is improving when severe smog blanketed the cities for days.

Some cities like Beijing started practicing regulations such as limiting the number of vehicles and suspending school on days with severe air pollution.