Hebei province in North China will see moderate to heavy air pollution from Saturday to Tuesday due to unfavorable weather conditions to disperse pollutants, the province’s air monitor forecast on Wednesday morning.

Influenced by unfavorable airflow, high humidity and temperature inversion, the air pollution is expected to linger in east and central south areas of the province for about four days, said Hebei Air Pollution Prevention and Control Office.

The province will issue an orange alert - the second-highest level in a four-tier system－ for heavy air pollution at 6 pm on Thursday and launch second-level emergency response actions accordingly.

This is the fourth time the province has issued alerts for heavy air pollution since October this year.

This round of smog is expected to hit 11 cities in the province, including the provincial capital city of Shijiazhuang, Baoding, Hengshui, Tangshan and the Xiongan New Area.

The smog will ease gradually on Nov 27 when a cold front arrives with better weather conditions to disperse pollutants.

The orange alert means the daily average AQI (air quality index) is forecast to exceed 200 for three consecutive days or longer.

When an orange alert is issued, industrial factories in the province are closed or their operations are restricted in order to reduce air pollutants.