Authorities in Beijing and many other Chinese cities extended the orange alert for heavy air pollution on Friday, as smog was expected to persist until the weekend.
Schools and other education institutions in the city have been ordered to stop outdoor courses and activities.
Many regions in China have been covered with heavy smog the past week.
On Tuesday, the national observatory issued a red alert for fog and renewed an orange alert for smog in a number of northern, eastern and central regions.
China has a four-tier colour-coded warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.
The smog in Beijing is expected to disappear on Saturday, offering relief from the polluted air that has engulfed the capital since Dec 30.
Other smog-engulfed provinces including Hebei, Henan and Shandong will see improvements on Sunday when winds come from the north, the Ministry of Environmental Protection said.
Story by the Associated Press and China Daily.