A Chinese woman wears a mask to protect from particles blown in during a sandstorm as she walks in the street on May 4, 2017 in Beijing, China. Sandstorms are common in northern China during the spring season and are caused when heavy winds from Mongolia in the north brings sand and pollutants that can blanket Chinese cities and cause air quality to deteriorate. (Photo by Kevin Frayer/Getty Images)

An Indian nomadic Gujjar girl hangs on to a horse cart after collecting bricks from debris on the outskirts of Jammu, India, Tuesday, March 7, 2017. The Gujjar tribal communities are considered by some to be economically and socially backward and the lack of care by the state government has led to resentment amongst the community. The tribe moves to the plains from the hills to escape the cold winters. (Photo by Channi Anand/AP Photo)

Nutrias venture near the camera at the river Nidda in Frankfurt am Main, Germany, 15 June 2017. The rabbit sized animals are often confused with biebers by amateurs. (Photo by Boris Roessler/DPA)

Young children at a Bristol, Great Britain health centre unsure of the benefits of sun-lamps and the special glasses that must be worn, July 1948. The health centre was part of the newly introduced free National Health Service. (Photo by Popperfoto/Getty Images)

A fellow officer comes to the aid of injured patrolman C.V. Satt, who was pelted with rocks and beer bottles during a clash between police and relief demonstrators in Denver September 23, 1935. (Photo by Henry G. Eisenhand/AP Photo)

Construction workers take a lunch break on a steel beam atop the RCA Building at Rockefeller Center, New York, September 29, 1932. In the background is the Chrysler Building. (Photo by AP Photo)

This photo provided by Netflix/naturepl.com and WWF-International shows an African Elephant (Loxodonta africana) in front of double rainbow, in Masai Mara, Kenya, included in the Netflix natural history series, “Our Planet”, in collaboration with Silverback Films and WWF. The eight-part series debuts in 2019. (Photo by Andy Rouse/Naturepl/WWF-International/Netflix via AP Photo)

Giant panda Meng Meng plays on a tree at a Siberian tiger-breeding base in Changchun, China on December 10, 2015. (Photo by Xu Chang/Xinhua Press/Corbis)