Beijing was blanketed by thick smog on Thursday, which put the city on a higher air pollution alert from yellow to orange. This also forced the city's dirtiest factories to cut fumes by 30 percent.
The capital raised its pollution alert from yellow to orange - the second-highest level on a four-tier warning system - at about noon, with the contamination remaining hazardous throughout the day.
Beijing's official Air Quality Index reached 470 at 4pm. A reading of over 300 is considered severe pollution.
Toxic smog also blanketed nearby cities - mostly in Hebei and Shanxi provinces - including Xingtai , Shijiazhuang , Dingzhou and Yangquan . Eighteen highways linking Beijing, Harbin and Shanghai had to be closed, according to the China Meteorological Administration.
Beijing is under tremendous pressure to tackle the haze, with the capital due to host a key political meeting in two weeks and the Asia-Pacific Economic Cooperation summit scheduled for early next month.