A sanitation worker in a mask cleans Tian'anmen Square amid the severe air pollution in Beijing, Dec 8, 2015. [Photo/IC]

What measures will be taken during a red alert?

Mandatory emergency measures and recommended emergency measures will be included in measures for the alert.

Mandatory emergency measures:

1. Vehicles excluding electric cars are only allowed on the roads based on odd or even license plate numbers, and the government will cut its use of vehicles by 30 percent, subway and bus services will extend operating hours and residents are encouraged to use the services.

2. Heavy goods vehicles, such as concrete transfer ones, are barred from the roads.

3. Activities at all construction sites are banned.

4. Roads will be cleaned at least once daily to reduce traffic dust pollution.

5. Fireworks and outdoor barbecues are banned.

Recommended emergency measures:

1. Schools and kindergartens will be closed. Enterprises are encouraged to adopt flexible working schedules for staff members.

2. Large-scale outdoor activities are banned in principle.

These measures cannot totally eliminate pollution, but they can effectively reduce the spike in pollution, according to environmental protection organs in Beijing.