A traffic police officer directs the traffic in Mohe City, northeast China's Heilongjiang Province, Dec. 29, 2019. Ice fog may appear when the temperature in Mohe, the "north pole" of China, plummets below minus 40 degrees Celsius in the morning of winter season. In order to ensure the safety of citizens' travel, Mohe traffic police have to work outdoors in extremely cold weather during the morning rush hour every day. (Photo by Tang Tiefu/Xinhua)