A primary school in Shijiangzhuang, capital city of North China's Hebei province, opened a indoor dome stadium on Sept 5, 2016, to filter out small smog particles. The venue, featuring a tennis court, is a recreational center for students during smog-stricken days. The stadium, covering an area of 1,000 square meters, can hold hundreds of students for physical education class.

Students attend a physical education class in the smog-free indoor stadium at Huaxing Primary School in Shijiazhuang, North China's Hebei province, Dec 9, 2016. [Photo/IC]