China's weather observatory issued an orange alert on Saturday evening for smog in the north of the country that will linger until Wednesday.
The alert was an upgrade from a yellow alert issued by the National Meteorological Center (NMC) earlier Saturday.
Beijing, Tianjin and the neighboring provinces of Hebei, Henan, Shanxi and Shandong will face persistent heavy air pollution, with southern Beijing, central and southern Hebei, northern Henan and western Shandong expected to face heavy smog, the NMC said.
The smog is predicted to ease on Wednesday in north China, the NMC said.
China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue.
The public has been warned to take protective measures when engaging in outdoor activities, and those who suffer from respiratory diseases are advised to stay indoors.
