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)

A tribal Fulani man milks a cow at a local milk collecting centre in Dangwala Karfi village on the outskirts of Nigeria's northern city of Kano January 19, 2016. (Photo by Akintunde Akinleye/Reuters)

Children sit under a crocodile based table, as they pose for photographers during a press preview of a themed auction that features the animal as artistic inspiration, entitled “Creatures Great and Small”, in London, Monday, December 15, 2014. The sale scheduled for December 17, 2014, explores animals across a diverse range of mediums and styles, from intricate carving details in 19th century furniture through to contemporary sculpture, according to Christie’s auction house. (Photo by Lefteris Pitarakis/AP Photo)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

Filipino typhoon survivor children, who escaped after their village was attacked by allegedly armed men, wait for social workers in the super typhoon devastated city of Tacloban, Leyte province, Philippines, 13 November 2013. Aid workers and relief supplies were being poured into eastern provinces hit by Typhoon Haiyan, which aid agencies and officials estimated has left thousands dead and staggering destruction in its wake. The official death toll in the Philippines from one of the world’s strongest typhoons rose to 1,833, the national disaster relief agency said with many towns still unaccounted for. (Photo by Dennis M. Sabangan/EPA)

The sun sets behind artist Luke Jerram's “Floating Earth” at Pennington Flash on November 22, 2021 in Wigan, England. The floating Earth will hover over Pennington Flash for 10 days from November 19, as part of a celebration of Wigan and Leigh's watercourses and is the first time one of Jerram's globes has been floated on an open expanse of water. (Photo by Christopher Furlong/Getty Images)

Snowfall views in Ercis district of Van, Turkiye on January 14, 2022. (Photo by Necmettin Karaca/Anadolu Agency via Getty Images)

The Aurora Borealis (Northern Lights) is seen in the sky in Ivalo of Lapland, Finland on September 27, 2019. (Photo by Alexander Kuznetsov/Reuters)