China maintained yellow alert for smog on Saturday as the pollution having choked most regions in the north showed little sign of abating.

On Saturday morning, PM 2.5 density in most parts of Beijing ranged between 260 and 400 micrograms per cubic meter, far above the safety standard set by the World Health Organization, according a statement on the National Meteorological Center (NMC) website.

Other regions, including Hebei, Shandong, Henan and Shaanxi provinces, will also be shrouded by heavy smog through Saturday before a cold front gradually disperses the pollution, the NMC forecasted.

Heavy rain will continue in the south. The statement reminds people to pay more regard to safety on the roads.

China has a four-tier warning system for severe weather, with red being the most serious, followed by orange, yellow and blue.