Beijing, together with the cities of Baoding, Handan, Langfang and Xingtai in the neighbouring Hebei Province, have issued red alerts, the most serious level of pollution.
The capital, a city of over 22 million people, is struggling with PM 2.5, the smallest and deadliest form of airborne particulate matter that almost touched 500, the highest category in the US Embassy pollution monitor which is regarded "hazardous", as it is several times higher than the levels prescribed by WHO.
"Affected by increased humidity and temperature inversion, the density of PM 2.5 may exceed 500 micrograms per cubic meter on Tuesday," Li Yunting, an environmental expert from BMEMC said.
The pollution level is expected to decrease to grade four, still hazardous for health, tomorrow, and the smog is expected to disperse on Thursday as a cold front arrives, BMEMC said, state-run Xinhua news agency reported.
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Kindergartens, middle schools and primary schools will also cancel classes tomorrow.
Key polluting industries will cut production as continuous cleaning operations are conducted in the capital city.
China's northern port city of Tianjin and other 12 cities from provinces of Hebei, Henan and Shandong have issued orange alerts.
Yellow alerts and blue alerts have been issued in 17 cities and 5 cities respectively, according to the air pollution emergency management headquarters of Beijing.
Tianjin will upgrade its orange alert to red from 0:00 a.M. Wednesday to 6:00 a.M. Thursday, according to a government statement.
Heavy smog has hit the country's Beijing-Tianjin-Hebei region on three occasions since late November.
Low wind speed, high humidity and unfavourable wind conditions are the main causes of the smog, Li said.