Taiyuan, capital the north China's coal-rich province of Shanxi, has issued a red alert for severe air pollution, and activated emergency measures at Friday midnight.
This is the 10th air pollution alert the city has issued this year and the first red alert, the most serious level, according to the city's environmental protection authority, which added that the smog will not disperse for six days, starting late Thursday.
The "odd-even" car restriction system, determined by the final digit of license-plates, has been initiated, and extra public transport has been organized in the meantime, with more buses running for longer.
Construction sites must halt work, certain factories will be ordered to cease production and schools advised to suspend classes for the duration of the red alert.
On Thursday, Beijing issued its first red alert for air pollution this year as heavy smog has been forecast to hit the city Friday.