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)

Andrew Hepher, Vice President of Lubricants Technology, Shell unveils the Shell Concept Car in Beijing, China, Friday, April 22, 2016. Built as proof of energy efficiency that can be achieved with the latest technologies, Shell unveiled the concept car ahead of the bi-annual Beijing Auto Show where the world's top car manufacturers will showcase their own upcoming products. (Photo by Ng Han Guan/AP Photo)

Soldiers of China's People's Liberation Army march with their weapons during a training session for a military parade to mark the 70th anniversary of the end of World War Two, at a military base in Beijing, China, August 22, 2015. Troops from at least 10 countries including Russia and Kazakhstan will join an unprecedented military parade in Beijing next month to commemorate China's victory over Japan during World War Two, Chinese officials said. The parade on September 3 will involve about 12,000 Chinese troops and 200 aircraft, Qi Rui, deputy director of the government office organizing the parade, told reporters in Beijing on Friday. (Photo by Damir Sagolj/Reuters)

A man inspects a plastic cover placed over an artwork attributed to Banksy on May 17, 2012 in London, England. The stencilled image depicts a poor child making Union Jack flags on a sewing machine and is located on the wall of a Poundland discount shop in the Wood Green area of north London. (Photo by Peter Macdiarmid)

An applicant try-out during a stewardess recruiting interview for China Southern Airlines on October 12, 2006 in Beijing, China. Over 160 candidates have competed at the Beijing Region selection for a total of 15 berths in the next stage of recruitment. The China Southern Airlines launched a nationwide campaign to single out qualified stewardesses, the first of its kind to recruit stewardesses through TV shows. (Photo by China Photos/Getty Images)

Models wait backstage before the Heaven Gaia Autumn/Winter 2021 collection show by Xiong Ying during China Fashion Week in Beijing, China on March 25, 2021. (Photo by Tingshu Wang/Reuters)

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)

People look at buildings displaying a light show on the eve of the 100th anniversary of the Chinese Communist Party in Beijing on June 30, 2021. (Photo by Noel Celis/AFP Photo)