BEIJING / Beijing authorities issued an orange alert for heavy air pollution which came into force on Monday at noon. The orange alert, the second highest in Beijing's warning system, is triggered when the city experiences two consecutive days of severe or three consecutive days of moderate air pollution.

A spate of emergency response measures will be implemented from Tuesday to Thursday, including mandatory traffic restrictions on heavy-polluting vehicles.

The Beijing Municipal Ecology and Environment Bureau has advised children, the elderly and those suffering from respiratory, cardiovascular or other chronic health conditions to stay indoors, and other people to reduce outdoor activities.

Unfavorable weather conditions are blamed for the smog blanketing Beijing and neighboring regions, the bureau noted.

The current round of air pollution in Beijing is expected to end on Friday, according to the weather forecast.