Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

Israeli soldiers of the Search and Rescue brigade take part in a training session in Ben Shemen forest, near the city of Modi'in May 23, 2016. (Photo by Amir Cohen/Reuters)

An elderly man uses a fan to shade himself from the sun as he walks in a public park in Beijing, Tuesday, June 7, 2016. Thursday marks the Duanwu Festival, a public holiday in China celebrated with outdoor activities including dragon boat races. (Photo by Mark Schiefelbein/AP Photo)

Selfie picture shows Swiss pioneer Bertrand Piccard during the last leg of the round the world trip with Solar Impulse 2 over the Arab peninsula July 25, 2016. (Photo by Jean Revillard/Bertrand Piccard/Reuters/SI2)

This November 11, 2014 aerial photo, shows a deforested area dotted with blue tarps, marking the area where miners reside, and craters filled with water, caused by illegal gold mining activities, in La Pampa, in Peru's Madre de Dios region. Less than a month before Peru plays host to global climate talks, the government sent a battalion of police into southeastern jungles to dismantle illegal gold-mining mining camps. Peru's anti-illegal mining czar, retired army Gen. Augusto Soto, marched the men to the wasteland known as La Pampa, where 50,000 hectares of rainforest have been obliterated in the past six years. (Photo by Rodrigo Abd/AP Photo)

Female North Korean soldiers parade to mark the 60th anniversary of the signing of a truce in the 1950-1953 Korean War at Kim Il-sung Square, in Pyongyang. (Photo by Jason Lee/Reuters)

5-year-old Rina Kumari rubs her eye while cracking stones on the banks of Mahananda river in Siliguri, northeast India, March 5, 2005. Over 400 million people in India live below the internationally agreed poverty line (living on less than US $1 per day). According to estimates, several hundred thousand children work as labourers and beg on the streets in India. (Photo by Desmond Boylan/Reuters)