Beijing, Jan 9 (TIWN) China's national observatory on Sunday issued a yellow alert for heavy fog in some regions of the country.

During the daytime on Sunday, thick fog is expected to sweep parts of Hebei, Shandong, Henan, Sichuan, Shanxi and Hubei provinces, according to the National Meteorological Centre (NMC).  Visibility in some affected areas will be reduced to less than 50 metres, Xinhua news agency quoted the NMC as saying.  It said drivers should slow down to safe speeds, and airports, freeways and ports should take appropriate safety measures.