Vehicles run in smog in Beijing, capital of China, Oct. 6, 2015. China's central observatory on Tuesday issued a yellow alert for smog to hit parts of north China, including Beijing, on Tuesday and Wednesday. (Xinhua/Liu Xianguo)

BEIJING, Oct. 7 -- Thick smog will continue to blanket parts of northern China on Wednesday.

Smog will persist in Beijing and Tianjin, cutting visibility to 1 km on Wednesday morning. Parts of Hebei, Shandong, Liaoning, Heilongjiang and Jilin will also experience smog.

The weather observatory renewed its yellow alert for smog on Wednesday. China has a four-tier color-coded weather warning system, with red representing the most severe weather, followed by orange, yellow and blue.

But a cold front will disperse the smog from Wednesday evening, said a forecast by the National Meteorological Center(NMC).

The NMC warned people in the affected areas to reduce outdoor activities.

The smog coincides with the last day of the week-long National Day holiday. It may aggravate the busy traffic as many return home from their travels.

The Chinese public has become increasingly sensitive to the health hazards of air pollution. To address public concern, the government aims to cut the density of inhalable particulate matter by at least 10 percent in major cities by 2017.