Light to moderate smog will blanket parts of northern, central and southwestern China from Sunday to Wednesday, the top observatory said Sunday.
Affected regions include Chongqing municipality and provinces of Anhui, Hebei, Henan, Shanxi, Shaanxi and Sichuan, said the National Meteorological Center.
Some areas may be hit by heavy smog, the center said.
The authority added that smog in Sichuan and Chongqing will abate or even disappear from Monday night under the influences of cold air and rain.
Local authorities in Sichuan and Chongqing on Sunday issued alerts for foggy weather, warning airports, freeways and ports to reinforce management to ensure safety.
