An injured girl reacts at a site hit by an airstrike in the rebel-held Douma neighbourhood of Damascus, Syria November 7, 2016. (Photo by Bassam Khabieh/Reuters)

Seals dressed in military uniforms swim during a show marking the 70th anniversary of the end of World War Two, at an aquatic park in the Siberian city of Irkutsk, Russia, May 9, 2015. (Photo by Evgeny Kozyrev/Reuters)

Mohamed Mostafa, 35, carries dyed yarns at a dye workshop in old Cairo, Egypt, March 17, 2016. Egypt's hard currency crisis and competition from modern factories in Asia and at home threaten one of the last dye workshops in Egypt. But one of its owners takes comfort in the trade's ancient resilience. Mohamed Mostafa boasts that the profession dates back 3,000 years, so it can survive anything. (Photo by Amr Abdallah Dalsh/Reuters)

In this Wednesday, March 18, 2015 photo, limestone quarry workers walk through a cloud of dust spewed into the air by rotor blades of the stone-cutting machinery in the desert of Minya, southern Egypt. Around 45,000 people, including children, work in an estimated 1,500 quarries, digging out stones that later will be used in construction or powdered to be used by pharmaceutical and ceramic companies. (Photo by Mosa'ab Elshamy/AP Photo)

A National Transitional Council (NTC) fighter fires an RPG during a street battle in the 700 complex area of “Emarat” against Muammar Gaddafi's troops on October 8, 2011 in Sirte, Libya. NTC fighters say this is the final assault on Muammar Gaddafi's home town as they capture the main hospital, University and the Ouagadougou conference centre in the city. (Photo by Majid Saeedi/Getty Images)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

Wizz Air's Airbus A-321 flying along the Danibe river during an air show in Budapest, Hungary, May 1, 2016. (Photo by Laszlo Balogh/Reuters)

Pedestrians cover their face as they walk along the dusty road in Kathmandu, Nepal February 27, 2017. Nepal has forced 2,500 old vehicles off roads in its capital city of Kathmandu, part of a fight against alarming air pollution levels that have hit nine times World Health Organisation (WHO) limits. Air pollution has been a chronic problem in rapidly growing Kathmandu, which sits in a Himalayan valley and is home to more than 3mn people. (Photo by Navesh Chitrakar/Reuters)