air pollution, 空氣污染

Schoolchildren wear masks as they leave school early at noon due to heavy air pollution, at a primary school in Shenyang, Liaoning province. According to Xinhua, lingering smog has disrupted traffic in northeast China's Liaoning Province, closing highways and delaying trains.
November 13, 2015
http://www.voanews.com/media/photogallery/day-in-photos-november-13-2015/3056759.html