Beijing is expected to be covered by smog for an entire week starting on Wednesday, the longest period of hazardous air pollution the city has encountered so far this year.
China's National Meteorological Center said Tuesday that the smog will spread to North China and the Yellow River-Huaihe River region.
The center said the worst pollution is expected to occur on Thursday and Friday and cautioned the public to make relevant preparations.
Air pollution has been a major concern for Beijing residents since the city saw the heaviest smog in years in November and December 2015, partly due to winter heating.
To curb air pollution, Beijing plans to build a web of ventilation corridors that facilitate air flow to blow away smog and pollutants, in addition to many other measures, authorities said in February.
The corridors will be created by connecting the city's parks, rivers, lakes and highways with green belts.
In 2015, the capital began replacing coal-fired power plants with cleaner energy plants and closed or limited production at more than 2,000 polluting factories. It also initiated its first-ever air pollution red alert system.
Air quality only improved marginally last year in the area around Beijing, data from the Ministry of Environmental Protection (MEP) suggests.
Beijing recorded 186 days of air quality that met standards in 2015, 14 more days than the year before, according to statistics from the MEP.
The annual average density of PM2.5 - particulate matter that causes hazardous smog - in Beijing stood at 80.6 micrograms per cubic meter, a year-on-year decrease of 6.2 percent.
