China's meteorological authorities on Wednesday issued a blue alert as smog cloaked most of the north and east of the country. A blue alert is the first of four warning levels.

A commuter braves the cold on a street blanketed by dense smog in Binzhou city, Shandong province, Jan 23, 2013. [Photo/Asianewsphoto]

Visibility in Beijing, Tianjin, West Shandong, North Henan, northern and central area of Hebei and Jiangsu is less than one kilometer with some areas reporting less than 200 meters.

The meteorological center said temperatures in most areas of North China will drop from due to a strong cold air.

Inner Mongolia autonomous region and Northeast China will be affected by snowfall and strong wind. Smog in North China and the Yellow-Huaihe River Valley will gradually dissipate as the cold air moves toward the south.