Alert issued for smog in central and eastern China

China's top observatory has issued a yellow alert for smog in most central and eastern areas. China has a four-tier warning system for smoggy weather, with red being the most serious, followed by orange and yellow.

The Central Meteorological Center says heavy smog will shroud northern parts of Beijing and Tianjin municipalities, the provinces of Hebei and Shanxi, as well as central and eastern parts of Henan, Shandong and Jiangsu provinces.

The public has been advised to take precautions as air pollution in some areas has already reached hazardous levels, and visibility has been reduced to less than 1-thousand meters. The good news is that a cold front is expected to bring rain and strong winds from Wednesday evening, which will help clear the smog.