The municipal air pollution emergency response office on Friday said that Beijing and neighboring regions will be hit by heavy air pollution due to adverse weather conditions.
The Beijing-Tianjin-Hebei region as well as the neighboring provinces of Shanxi, Shandong and Henan will be affected by the smog, according to the Ministry of Ecology and Environment.
It is expected that the density of PM2.5 will stay above 200 micrograms per cubic meter from Sunday evening to Monday morning. The air quality will have improved by Monday evening.
Under Beijing's current three-tier warning system, yellow alert is the least severe, followed by orange and red.
Yellow alert and above will trigger a series of compulsory emergency responses including the suspension of outdoor construction operations to reduce dust, the restriction of heavy-polluting vehicles or the suspension of production in smokestack industries.
