BEIJING, Dec. 7 (Xinhua) -- Heavy haze still shrouded north and east China on Saturday, with highways closed and flights delayed or canceled.

The smoggy weather affected a large swathe of the country's land from north to south, including Beijing, Hebei, Shandong, Jiangsu, Shanghai, Zhejiang, Hunan, Guangxi and Guangdong, with visibility less than 50 meters in some regions.

Cities like Shanghai and Nanjing have been enveloped in the grey sky for the past several days. Many pedestrians had to wear masks.

Beijing saw smog on Saturday. Local meteorological authorities forecast a cold front will reach Beijing on Sunday afternoon, which will quickly improve the air quality.