Participants climb over a wall at the “Tough Mudder” endurance event series in Arnsberg September 6, 2014. Competitors who took part in the endurance event saw themselves having to overcome various military style obstacles. (Photo by Ina Fassbender/Reuters)

Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

Professor Xie Yong works on an art installation of a beaver, which is made out of plastic and around 300,000 needles, in Shenyang, Liaoning province, July 23, 2013. The needles, according to Xie, represent the pain felt by animals when their fur is taken off to produce clothing. (Photo by Reuters/Stringer)

A boy jumps from a swing during sunset in Valras-Plage, southern France December 29, 2014. (Photo by Yves Herman/Reuters)

A worker walks through a salt pan on the eve of May Day or Labour Day on the outskirts of the southern Indian city of Chennai April 30, 2014. India is the third largest salt producing country in the world after China and U.S. with global annual production about 230 million tonnes, according to government data. (Photo by Reuters/Babu)

Bystanders look at MV Wakashio bulk carrier that had run aground and from which oil is leaking near Blue Bay Marine Park in south-east Mauritius on August 6, 2020. The carrier, belonging to a Japanese company but Panamanian-flagged, ran aground on July 25 and its crew was evacuated safely. The ship was empty at the time but was carrying 200 tonnes of diesel and 3,800 tonnes of bunker fuel, according to the local press. (Photo by Dev Ramkhelawon/L'Express Maurice/AFP Photo)

Police officers wield their batons against activists from various student unions during a protest march demanding jobs and better education facilities, in Kolkata, India, February 11, 2021. (Photo by Rupak De Chowdhuri/Reuters)