WUHAN, Jan. 18 (Xinhua) -- Central China's Hubei Province issued an orange alert Thursday for continuous smog blanketing the region.

Thick smog with visibility of less than 200 meters appeared in parts of Hubei Thursday, according to the provincial environmental monitoring center.

The smog will continue to spread to other areas, and the air quality in the province is unlikely to see significant improvement, the provincial meteorological station said.

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