In Beijing, the air has been noticeably hazy for several days. The Beijing Meteorological Bureau on Wednesday morning issued a code yellow alert to warn residents of smog in several districts via its weibo account.
It is the first smog to hit the capital since the APEC Economic Leaders' Week ended on November 12.
The alert warned that Daxing, Tongzhou and Fangshan districts would be shrouded by smog from Wednesday to Thursday.
On Thursday, the central and southern part of the city was particularly hard hit by severe air pollution, according to the NMC.
During the APEC meetings, Beijing had been free of smog as emission-heavy production drew to a halt and half of cars across the capital were banned to lessen pollution.Â