BEIJING - Serious pollution is expected to remain over Beijing and surrounding areas until the middle of the month, Chinese state media said.
Tens of millions of people in the capital and surrounding areas have this week been hit by some of the region's worst prolonged smog in months.
On Wednesday, Beijing's concentrations of hazardous PM 2.5 particles were more than 20 times higher than World Health Organisation guidelines, air quality monitoring firm IQAir said.
And the Chinese capital was the third most polluted major city in the world, the firm said, just ahead of Bangladesh's capital Dhaka.
In response to the smog, authorities have taken steps to limit the activity of heavy-emitting vehicles and encouraged residents to remain indoors.
Chinese officials were cited by the state-run Beijing Daily as saying that "moderate" and "severe and above" levels of pollution were expected to affect the Beijing-Tianjin-Hebei area until mid-November.
The area is home to more than 100 million people.
A "moderate" pollution ranking still means pollutants in the air are well over WHO-recommended limits.
The forecasts for the region were based on joint analysis conducted by the China National Environmental Monitoring Centre and local meteorological authorities across the country.
"The primary pollutants (in the Beijing-Tianjin-Hebei region) are PM2.5 and PM10," the report said.