China on Saturday issued a yellow alert for smog as the pollution choked most regions in the country's north with no signs of abating.
Parts of north China will see the worst smog so far this year the National Meteorological Centre said on Saturday.
Beijing's sky was gloomy and the ground largely deserted.
The fine particulate matter PM2.5 touched 304 micrograms per cubic metre on Saturday, which is regarded very unhealthy specially for people with heart and lung problems.
Beijing braces for a 30-year low of minus 16 degrees Celsius from Saturday through Sunday, the Beijing meteorological station said.