On Thursday, the Beijing municipal government issued a red alert for air pollution, the first since the beginning of this year.

There is a four-tier warning system for air pollution in China: blue, yellow, orange, red, in rising severity.

The current red alert will last for five days from 8 pm on Saturday. During this period, the strictest restrictions have been implemented in Beijing for enterprises and private vehicle owners. Some industrial operations are suspended and cars are allowed on the roads on alternate days depending on whether their license plate number ends in an odd or even number so as to reduce vehicle emissions.

Local residents are advised to stay indoors, and kindergartens and primary schools have suspended classes.

Since the beginning of Autumn, China's northern area has been facing ever more severe air pollution especially after the heating supply began in November.

Besides Beijing, several other cities and regions, in North China, have been advised to follow the emergency response measures Beijing has implemented, in order to fight against the smog.