China's national observatory on Saturday issued a yellow alert for smog in some northern regions, the second bout of smog this week.
Moderate to heavy smog will be seen across the Beijing-Tianjin-Hebei region, as well as some areas in the provinces of Henan, Shanxi and Shandong from Saturday evening to Sunday, according to the National Meteorological Center (NMC).
People in those areas have experienced bad air quality from Wednesday to Thursday before smog in some parts was dispersed by a cold front.
The NMC blamed the unfavorable weather condition for not properly dispersing air pollutants as a reason for the new bout of smog, adding that the pollution will likely be lifted by cold front that may arrive on Monday.
The center warned that people with respiratory issues should reduce outdoor activities or wear a mask when in the open air.
China has a four-tier color-coded system for severe weather, with red being the most serious, followed by orange, yellow and blue.
