![Blue alert engaged for dust clogging the air in Beijing(5/11)](http://www.ecns.cn/hd/2018/03/29/a2937bb002ed4adeafc6f0fb0928d359.jpg)
A road sweeper works in the dusty weather, and the sign on the car reads "heavy air pollution, emergency response operation" in Beijing on March 28, 2018. (Photo: Li Hao/GT)
A road sweeper works in the dusty weather, and the sign on the car reads "heavy air pollution, emergency response operation" in Beijing on March 28, 2018. (Photo: Li Hao/GT)