China's weather observatory has issued an orange alert for smog in the country's north that will last through Tuesday evening.

Beijing, Tianjin, parts of the neighboring provinces of Hebei, Henan and Shandong, as well as Shanxi, Shaanxi and parts of Jiangsu and Anhui provinces in east China will face moderate smog, with south Beijing to experience heavy smog, the National Meteorological Center (NMC) said.

Beijing issued its first red alert for air pollution on Monday evening, which means it has to cope with heavy pollution in the next three days.

China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue. Endi