Muslim pilgrims pray on top of the rocky hill known as Mountain of Mercy on the Plain of Arafat during the annual hajj pilgrimage near the holy city of Mecca, Saudi Arabia, Thursday, July 30, 2020. Only about 1,000 pilgrims will be allowed to perform the annual hajj pilgrimage this year due to the virus pandemic. (Photo by Saudi Ministry of Media via AP Photo)

People cool off in a fountain outside the Southbank Centre on June 30, 2015 in London, England. The UK is currently experiencing a heatwave, with temperatures of 35 degree celsius forecast tomorrow in some parts of the country. The extreme heat has already seen train cancellations and a health warning has been issued. (Photo by Rob Stothard/Getty Images)

A prisoner from the Pedrinhas prison is carried to receive medical help after he was injured during a fight between rival gangs inside the jail, in Sao Luiz, capital of Maranhao state, January 8, 2014. The recent posting on a major Brazilian news website of a video filmed last December 17 by Pedrinhas prisoners of the decapitated and tortured bodies of rival inmates inside the jail has highlighted some of the problems present in the country's prison system which houses nearly twice as many prisoners as its capacity, according to official statistics. (Photo by Douglas Cunha/Reuters/O Estado do Maranhão)

Emma White, of Team Cyclocrossworld, hits the dirt hard during the USA Cycling Cyclo-cross National Championship Elite Women's race at the Valmont Bike Park in Boulder, Colorado, on January 12, 2014. (Photo by Jeremy Papasso/The Daily Camera)

German police officers take pictures as fireworks explode next to the Quadriga sculpture atop the Brandenburg gate during New Year celebrations in Berlin, Germany, January 1, 2017. (Photo by Fabrizio Bensch/Reuters)

Migrant children run away from clashes with Mexican National Guards after their group crossed the Suchiate River on foot from Guatemala to Mexico, on the riverbank near Ciudad Hidalgo, Mexico, Monday, January 20, 2020. More than a thousand Central American migrants hoping to reach the United States marooned in Guatemala are walking en masse across a river leading to Mexico in an attempt to convince authorities there to allow them passage through the country. (Photo by Santiago Billy/AP Photo)

Chelyabinsk Airport employees take part in an exercise to evacuate aircraft passengers showing symptoms of the 2019-nCoV pneumonia-like coronavirus on February 5, 2020. (Photo by Nail Fattakhov/TASS)

Mothers-to-be show their belly paintings in Hefei, east China's Anhui province on May 8, 2020. (Photo by Rex Features/Shutterstock/China Stringer Network)