Pakistan girls make selfies holding a Pakistan-made weapon displayed at the four-day International Defence Exhibition and Seminar (IDEAS) 2016 in Karachi, Pakistan, Wednesday, November 23, 2016. (Photo by Shakil Adil/AP Photo)

A plane battling the Ferguson Fire passes the setting sun in unincorporated Mariposa County Calif., near Yosemite National Park on Sunday, July 15, 2018. (Photo by Noah Berger/AP Photo)

Vehicles pass through the heavy fog and air pollution that cover Skopje valley in the early morning, in Skopje, The Former Yugoslav Republic of Macedonia, 14 December 2017. According to media reports, Skopje is considered one of the most polluted cities in the world. (Photo by Georgi Licovski/EPA/EFE)

An artist gets ready backstage to perform an Indian art form of dance called “Ottamthullal” at the annual eight-day long Vrischikolsavam festival, which features a colourful procession of decorated elephants along with drum and trumpets concerts, at Sree Poornathrayeesa temple in Kochi, India, December 7, 2018. (Photo by Sivaram V/Reuters)

A man stands by an installation depicting “2019” in the Red Square in Moscow, Russia on December 17, 2018. (Photo by Maxim Shemetov/Reuters)

Models struggle against strong wind before the rehearsal of Christian Dior's Haute Couture Spring-Summer 2017 live show to celebrate Dior's new flagship store at the rooftop of Ginza Six mall in Tokyo, Japan, April 19, 2017. (Photo by Toru Hanai/Reuters)

Hindu devotees (not pictured) touch a child with their feet as part of a ritual to bless him during a religious procession held to mark the Gajan festival in Kolkata, India, April 13, 2018. (Photo by Rupak De Chowdhuri/Reuters)

A demonstrator confronts riot police during a rally in defense of the nationalization of lithium reserves in the country, in Santiago, Chile on January 29, 2018. (Photo by Pablo Sanhueza/Reuters)