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)

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)

Racegoers in fashionable hats attend Ladies Day at Cheltenham Festival on March 15, 2017 in Cheltenham, England. (Photo by David Davies/PA Wire)

A child dressed as a Roman centurion poses during a parade to mark the anniversary of the foundation of Rome in 753 BC, on April 23, 2017 in Rome. (Photo by Alberto Pizzoli/AFP Photo)

Arrow sports his new elastic booties at a PetSmart in Tempe, Ariz. on Tuesday, June 20, 2017. Phoenix radio station KSLX handed out the protective coverings to protect dogs' paws from the hot pavement, as temperatures in Phoenix are forecasted to hit 120 degrees (48°C). (Photo by Angie Wang/AP Photo)

Kim Kardashian goes shopping for gummy bears in sheer Gucci bra on October 9, 2017. She paired the risqué outfit with a waist-fitted midi length pencil skirt and clear lucite wedges from Kanye West’s fashion line. (Photo by Splash News and Pictures)

Aerial view of pond cypress at Qinglongwan Forest Park near Ningguo, China on November 26, 2017. (Photo by Imaginechina/Rex Features/Shutterstock)