A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

Tourists walk above a tea plantation in Enshi, Hubei province, December 27, 2015. (Photo by Reuters/Stringer)

A train attendant helps a passenger to adjust her seat at the business class carriage on a CRH 380A bullet train Thursday, June 16, 2011. (Photo by Reuters/China Daily)

In this Wednesday, April 8, 2020, photo, youths remove their mask to record a dance routine on the streets of Wuhan in central China's Hubei province. Released from their apartments after a 2 1/2-month quarantine, residents of the city where the coronavirus pandemic began are cautiously returning to shopping and strolling in the street but say they still go out little and keep children home while they wait for schools to reopen. (Photo by Ng Han Guan/AP Photo)

A vendor wearing a protective face mask looks out of her store selling sugar-coated haws on a stick in Beijing, Sunday, April 12, 2020. (Photo by Andy Wong/AP Photo)

Giant pandas play in the snow at the Shenshuping Base of China Conservation and Research Center for the Giant Panda on January 13, 2022 in Aba Tibetan and Qiang Autonomous Prefecture, Sichuan Province of China. (Photo by Chen Xianlin/VCG via Getty Images)

A man walks with a Cyberdog, produced by Chinese tech company Xiaomi, on February 19, 2022 in Beijing, China.The quadruped robots, often owned by tech and robotic enthusiasts, do not have a specific purpose so far, but the open source nature of the robots could make them suitable for several applications in the future. (Photo by Andrea Verdelli/Getty Images)

Primary school students attend an emergency evacuation drill on China's national day for disaster prevention and relief on May 12, 2022 in Hefei, Anhui Province of China. China's national day for disaster prevention and relief falls on May 12 every year. (Photo by Ge Qingzhao/VCG via Getty Images)