China has issued the first smog warning of the winter for the Beijing - Tianjin - Hebei region for 24 to 26 November . The yellow alert , issued by the Beijing Municipal Bureau of Ecology and Environment , means that heavy industry and construction sites will have to stop operating for the period . Additionally , 28 cities in Hebei , Shanxi , Sichuan and Henan province have issued orange - level smog warnings for the same period . Northern China often sees heavy smog over the winter season, which runs from mid-November to mid-March, as homes and power utilities burn more coal for power and heating. Heavy industry is a problem for China 's northern region from mid - November to mid - December because of additional coal burning for power and heating by homes and utilities .
China has issued the first smog warning of the winter for the Beijing - Tianjin - Hebei region for 24 to 26 November . The yellow alert , issued by the Beijing Municipal Bureau of Ecology and Environment , means that heavy industry and construction sites will have to stop operating for the period . Additionally , 28 cities in Hebei , Shanxi , Sichuan and Henan province have issued orange - level smog warnings for the same period . Heavy industry is a problem for China 's northern region from mid - November to mid - December because of additional coal burning for power and heating by homes and utilities .