BEIJING, Nov. 21 -- Beijing, Tianjin and cities in neighboring Hebei Province will likely see persistent heavy air pollution for up to five days, according to the Ministry of Environmental Protection.

Between Nov. 22 and 26, air pollution in the central and southern part of the notoriously polluted Beijing-Tianjin-Hebei region is likely to reach the "heavy" and "grave" categories -- the top two severity levels, according to the ministry statement released Friday.

It cited PM 2.5 as the main pollutant for the period.

In Beijing, the air has been noticeably hazy for several days.

Meanwhile, air quality in the northern part of the region is forecast in the range of fine to light pollution, with occasional medium pollution.

The ministry advised children, the elderly and people with respiratory issues to stay indoors in the mean time while encouraging people to choose public transports instead of cars.

It urged local environmental departments to closely monitor pollution index and prepare to take emergency measures such as traffic limits in the case of severe pollution.