A family member of a torch relay runner wearing a protective mask uses a portable electric fan to cool down as she attends a torch kiss event during Tokyo 2020 Olympic torch relay celebration at Shinagawa Central Park in Tokyo, Japan, July 21, 2021. (Photo by Issei Kato/Reuters)

A migrant worker wearing face masks to help curb the spread of the coronavirus walks up to a pedestrian bridge in Beijing, Sunday, December 6, 2020. Provincial governments across China are placing orders for experimental, domestically made coronavirus vaccines, though health officials have yet to say how well they work or how they may reach the country's 1.4 billion people. (Photo by Andy Wong/AP Photo)

(L-R) Dustin Poirier punches Conor McGregor of Ireland in a lightweight fight during the UFC 257 event inside Etihad Arena on UFC Fight Island on January 23, 2021 in Abu Dhabi, United Arab Emirates. (Photo by Jeff Bottari/Zuffa LLC)

Metropolitan Police patrol as people party at the Soho district, as the coronavirus disease (COVID-19) restrictions ease, in London, United Kingdom on April 16, 2021. Pubs and Restaurants are expecting good business tonight being the first Friday night after Coronavirus lockdown rules were relaxed to allow outside dining and drinking. (Photo by Henry Nicholls/Reuters)

Nepalese army personnel pay tributes before the body of a person who died of COVID-19 before cremating the same in Kathmandu, Nepal, Monday, August 17, 2020. (Photo by Niranjan Shrestha/AP Photo)

A Saudi trader wears a mask as he monitors stock information at the Saudi stock market in Riyadh, Saudi Arabia on August 25, 2020. (Photo by Ahmed Yosri/Reuters)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

An Israeli soldier of the Caracal battalion smiles during a 23-kilometer march marking the end of their training in Israel's Negev desert, near Kibbutz Sde Boker February 14, 2013. The “Caracal” battalion, two-thirds of whose members are women, was established in 2004 with the purpose of incorporating female soldiers in combat units. The main mission of Caracal is routine patrols on Israel's border with Egypt to intercept infiltrators and smuggling from the Sinai desert. (Photo by Darren Whiteside/Reuters)