British Prime Minister Boris Johnson visits the Pavegen stand, a company that converts footsteps into energy, at the Innovation Zone during the UK-Africa Investment Summit in London, Britain on January 20, 2020. (Photo by Leon Neal/Pool via Reuters)

Chinese epidemic control workers wear protective suits as they disinfect each other after performing nucleic acid swab test for COVID-19 on citizens at a government testing site in Xicheng District during an organized tour on June 24, 2020 in Beijing, China. While Chinese government medical officials have said they believe they have controlled the spread, authorities are trying to contain the outbreak linked to the Xinfadi wholesale food market, Beijing's biggest supplier of produce and meat. (Photo by Kevin Frayer/Getty Images)

Lizzy Huggler, 20 ,wears blue ties on her legs on the third day of the Firefly Music Festival in Dover, Delaware U.S., June 16, 2018. (Photo by Mark Makela/Reuters)

Dancers perform inside of transparent balls during the Botanical Night at Botanical Garden in Berlin, Germany, 20 July 2018. During the Botanical Night a 16 kilometre long path along the flower beds and several themed gardens are illuminated and guide to many attractions. (Photo by Hayoung Jeon/EPA/EFE)

A handout photo made available by the NASA shows the United Launch Alliance Delta IV Heavy rocket launches NASA's Parker Solar Probe to touch the Sun, from Launch Complex 37 at Cape Canaveral Air Force Station, Florida, USA, 12 August 2018. Parker Solar Probe is humanity’s first-ever mission into a part of the Sun’s atmosphere called the corona. Here it will directly explore solar processes that are key to understanding and forecasting space weather events that can impact life on Earth. (Photo by Bill Ingalls/EPA-EFE/NASA)

Model Cara Delevingne walks the runway during the Balmain show as part of the Paris Fashion Week Womenswear Spring/Summer 2019 on September 28, 2018 in Paris, France. (Photo by David Fisher/Rex Features/Shutterstock)

A guest takes a selfie during the show of Laura Biagiotti at the Milan Fashion Week, in Milan, Italy, 24 February 2019. The Fall-Winter 2019/20 Women's collections are presented at the Milano Moda Donna from 20 to 25 February 2019. (Photo by Matteo Bazzi/EPA/EFE)

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)