A showgirl in a face mask stands by the door at the reopening of Bally's Las Vegas hotel and casino, Thursday, July 23, 2020, in Las Vegas. The casino reopened for the first time since March following a closure to prevent the spread of the coronavirus. (Photo by John Locher/AP Photo)

People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

Commuters wearing face masks jostle for a ride on a bus discarding social distancing guidelines in Kolkata, India, Tuesday, July 21, 2020. With a surge in coronavirus cases in the past few weeks, state governments in India have been ordering focused lockdowns in high-risk areas to slow down the spread of infections. (Photo by Bikas Das/AP Photo)

It doesn’t make for the most flattering photoshoot, but there is a reason these zebras at Lewa wildlife conservancy in Kenya in the second decade of August 2025 are stood head to tail: they use their tails to swat flies from each others’ faces. (Photo by Andrew Campbell/Solent News & Photo Agency)

A woman wearing a face mask to help curb the spread of the coronavirus gets fever checked before going into the Pyongyang Railway Station in Pyongyang, North Korea, Thursday, August 13, 2020. (Photo by Jon Chol Jin/AP Photo)

Tour de France hostess wear face masks prior to the start of the first stage of the Tour de France cycling race over 156 kilometers (97 miles) with start and finish in Nice, southern France, Saturday, August 29, 2020. (Photo by Christophe Ena/AP Photo)

A Filipino climate activist wearing a face shield with the words “Climate Justice Now” poses showing her hand as part of global climate change protests, in Quezon City, Metro Manila, Philippines on September 25, 2020. (Photo by Eloisa Lopez/Reuters)

A person wearing a face mask is reflected in an art work entitled “A=V” by Ben Cullen Williams, amid the coronavirus disease (COVID-19) outbreak, in Covent Garden, London, Britain on October 16, 2020. (Photo by John Sibley/Reuters)