A new round of moderate to heavy smog will hit central and eastern regions of China on Sunday and last three days, posing negative impacts on the Spring Festival travel rush, according to Weather.com.cn, a weather service website hosted by the Public Meteorological Service Center of China Meteorological Administration (CMA).

Ten provinces and municipalities will be affected, including Beijing, Tianjin, Hebei, Henan and Shandong.

Forecasts by the National Meteorological Center of the CMA show that air will remain stable from January 15 to 17 in these regions, where smog is expected to worsen. January 16 and 17 will witness the worst smog, with moderate to heavy air pollution choking Beijing, Tianjin, and parts of the Hebei, Henan, Shandong, Shanxi and Shaanxi Provinces, as well as northeast China.

Due to increasing relative humidity close to the ground, the central and southern parts of north China and the Huanghuai region (the area south of the Yellow River and north of the Huai River) will be shrouded in heavy fog on January 15-17, reducing visibility to less than 200 meters at night and in the morning. The smog will gradually weaken or dissipate from north to south on January 18 when a cold air front is expected to arrive.

This will be the second round of smog affecting large areas of China this year, just about a week after the previous one, which had lasted over ten days in many regions.

For passengers returning home for the incoming Chinese New Year, the arrival of smog will not be good news. Zhao Chenxin, a spokesman of the National Development and Reform Commission, said on Thursday that uncertain weather this winter would bring challenges to ensuring a smooth holiday travel rush.

Smog, especially in the winter, has been a headache to Chinese residents, despite efforts made by authorities to cut emissions. Although the average concentration of PM 2.5 particles fell by about 30 percent in 2016, compared with 2013 in the Beijing-Tianjin-Hebei region and neighboring provinces, the area hit hardest by smog, there seems to be little air quality improvement in winter, said Chen Jining, Minister of Environmental Protection at a recent press conference.

The regions are major coal consumers and home to a large share of China's steel, coke and cement production as well as automobiles, according to Chen. He added that unfavorable weather conditions and inefficient winter heating had also contributed to lingering smog.