Two women look at a mobile phone as they stand on Tiananmen Square during a sand storm in heavily polluted weather in Beijing on February 28, 2013. Beijing residents were urged to stay indoors as pollution levels soared before a sandstorm brought further misery to China's capital. (Photo by Ed Jones/AFP Photo)

A vehicle is trapped in a flooded street during a rainstorm in Beijing city on June 23, 2011 in Beijing, China. Heavy rain that hit Beijing on Thursday afternoon has disrupted traffic and caused flooding low-lying areas. (Photo by ChinaFotoPress/Getty Images)

People dressed as a “Chinese Dragon”, swim in water at the Beijing Aquarium on January 5, 2012 in Beijing, China. The new year in Chinese calendar is the year of Dragon which will fall on January 21, 2012. (Photo by ChinaFotoPress/Getty Images)

Tiffany Porter of Britain falls after competing in the women's 100 metres hurdles final during the 15th IAAF World Championships at the National Stadium in Beijing, China August 28, 2015. (Photo by David Gray/Reuters)

Second placed Zhang Guowei of China gestures as he celebrates after winning silver in the men's high jump final during the 15th IAAF World Championships at the National Stadium in Beijing, China, August 30, 2015. (Photo by Dylan Martinez/Reuters)

Italy's Louis Phillip Vito III falls as he competes during the men's halfpipe qualification round at the 2022 Winter Olympics, Wednesday, February 9, 2022, in Zhangjiakou, China. (Photo by Francisco Seco/AP Photo)

The Temple of Heaven (The Qi Nian Temple) is illuminated as Beijing celebrates the New Year's Eve at the Temple of Heaven Park on December 31, 2011 in Beijing, China. (Photo by Lintao Zhang/Getty Images)

This picture taken on February 23, 2014 shows participants wearing dresses running half-naked in the annual 3.5 km Undie Run held in the Olympic Forest Park smog-covered Beijing. Some 200 participants took part in this event, many of them with gas masks, as dangerous smog blighted swathes of northern China in recent days. (Photo by AFP Photo/STR)