A woman wearing a mask walk in a street in a Yonghegong Lama temple compound seen shrouded in smog in Beijing, China, 30 November 2015. Beijing issued an orange alert for heavy smog 30 November, the highest level this year. Authorities in the Chinese capital warned of 'severe pollution' and advised the capital's 20 million inhabitants to stay indoors. (Photo by How Hwee Young/EPA)

A worker holds the head of a fox while killing it with electricity for its fur at a fox farm in Nanzhuang village, Shandong province, China, December 11, 2015. There are over 60 households in the village still raising foxes, raccoon dogs and other animals for the fur trade. China is the world's largest fur producer and exporter, according to state media. (Photo by William Hong/Reuters)

Participants pose as they take part in a bodybuilding and fitness event named “China Fit”, in Beijing, China, June 15, 2016. (Photo by Reuters/Stringer)

Taiwanese and Chinese nationals suspected of telecom fraud are surrounded by China police SWAT team and Cambodia police as they were deported to China at the International Airport of Phnom Penh, June 24, 2016. Scores of Chinese police officers swarmed the tarmac at Phnom Penh International Airport on Friday as 39 suspects arrested for their involvement in an alleged telecom scam were herded onto a chartered plane bound for China – including 25 Taiwanese nationals, whose government unsuccessfully attempted to have them repatriated. (Photo by Samrang Pring/Reuters)

A string is used to ensure that the skirts of female members of the honour guard are in the same height from the ground as they prepare for a welcoming ceremony for Congo Republic President Denis Sassou Nguesso outside the Great Hall of the People in Beijing, China, July 5, 2016. (Photo by Jason Lee/Reuters)

A boy rides on a snow wagon towed by a robot dressed as a Teddy bear, which only moves forward by moving its legs, during the Ice and snow carnival at Taoranting park in Beijing February 9, 2015. (Photo by Kim Kyung-Hoon/Reuters)

People pass a suitcase as they line up to enter a railway station in Beijing, February 15, 2015. Chinese Ministry of Transport said a total of 2.807 billion trips are expected to be made during the 40-day Spring Festival travel rush, which started on February 4 and will last until March 16, Xinhua News Agency reported. (Photo by Reuters/Stringer)

A migrant carries his belongings as he arrives at the Beijing railway station to catch a train in Beijing, Friday, February 13, 2015. (Photo by Andy Wong/AP Photo)