China's weather observatory on Friday issued a yellow alert for smog in the country's northern regions.
Beijing, Tianjin, and parts of the neighboring provinces of Hebei, Henan and Shandong will be shrouded in moderate smog from Friday evening to Saturday, the National Meteorological Center (NMC) forecast.
Heavy fog will blanket these regions, with visibility of less than 500 meters in some areas, according to the NMC.
China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue.
