A man wearing a mask rides on Chang'an Avenue in Beijing, capital of China, May 4, 2017. [Photo/Xinhua]

Sandstorms were also reported in north China's Hebei Province and are expected to clear from Friday thanks to wind expected Saturday.

Parts of Beijing, as well as Gansu, Heilongjiang, Jilin, Shaanxi and Shanxi provinces and the autonomous regions of Inner Mongolia, Ningxia and Xinjiang will also see sandstorms from Thursday to Friday, said the National Meteorological Center.

Zhu Jiang, head of the Institute of Atmospheric Physics of the Chinese Academy of Sciences, said the sandstorms had traveled from Mongolia.

Ejin Banner of Alxa League saw the first sandstorm on Wednesday, with visibility reduced to less than 100 meters.

Strong wind reduced temperatures in the region by about four degrees Celsius. Local weather stations warned residents to keep their doors and windows closed, to buttress sheds and billboards, avoid riding bicycles and to remain alert for forest fires.

China has a four-tier color-coded system for severe weather, with red being the most serious, followed by orange, yellow and blue.