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 tourist poses for a picture with the Sphinx at the Pyramids of Giza in Cairo, Egypt, on October 19, 2011. (Reuters/Jamal Saidi)

The Kung Fu Panda balloon is lifted before the 86th Annual Macy's Thanksgiving Day Parade November 22, 2012 in New York City. Macy's donated tickets and transportation to this year's Thanksgiving Day Parade to 5,000 people from neighborhoods hardest hit by Superstorm Sandy. (Photo by Charles Sykes/Associated Press)

Donny Golden shares a laugh with dancers from the Irish American Society during the 250th annual St. Patrick's Day parade March 17, 2011 in New York City. The parade honors the patron saint of Ireland and marched for the first time in the U.S. on March 17, 1762, fourteen years before the Declaration of Independence.

A glass is checked at the table for China's top leaders before the start of a reception to celebrate National Day at the Great Hall of the People in Beijing, China September 30, 2016. China celebrates its National Day on October 1. (Photo by Damir Sagolj/Reuters)

A worker piles salvaged e-bikes and scooters on the back of his three wheeler before taking them to be recycled on August 31, 2021 in Beijing, China. (Photo by Kevin Frayer/Getty Images)

A Chinese couple take pictures in an interactive installation art work named “You and Me” on Valentine's Day at 798 Art Zone on February 14, 2012 in Beijing, China. (Photo by Feng Li/Getty Images)

Employees wear "No-Face" masks during working hours at a service company in Handan, Hebei Province of China. As a service company, staff must smile to customers every day. On “No-Face Day”, staff wore masks to hide their facial expressions and allow them to relax. No-Face is a character in the 2001 animated movie “Spirited Away”, a silent masked creature who has no facial expressions.