Beijing recorded an AQI close to or above 500, the top of the scale, on Sunday. Cold air helped disperse the smog on Monday morning, but the effect was short lived.
The capital raised its orange alert for air pollution on December 30 and has extended it until Wednesday. An orange alert is the second-highest level on a four-tier warning system. Heavily polluting vehicles and trucks carrying construction waste are banned from roads and some manufacturing firms have cut production.
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The pollution disrupted traffic over the three-day New Year's holiday. The toll station near the capital on the Beijing-Hong Kong-Macau expressway reported numerous stationary vehicles, making the highway around the station look like a car park.
Several highways in Henan were closed due to low visibility, which had dropped down to as little as 50 metres in some parts of the province.
Kindergartens, middle and primary schools in Zhengzhou, the provincial capital, were to be closed today. Similar measures were taken in Xian, the capital of Shaanxi province.