A man drinks a Frucola as a policeman chases demonstrators during a protest against Chile's government in Santiago, Chile on December 4, 2019. (Photo by Goran Tomasevic/Reuters)

The Royal Castle is seen a veil of heavy winter smog in Budapest, Hungary on January 30, 2017. (Photo by Laszlo Balogh/Reuters)

People in Kathmandu joke that the face mask has now become part of the national dress – an indispensable accessory in an effort to protect themselves from the dust. Nepal has the worst air quality in the world, according to the Environmental Performance Index. (Photo by Pete Pattisson/The Guardian)

Men ride a scooter through a flooded street after heavy rains in New Delhi, India, August 6, 2019. (Photo by Adnan Abidi/Reuters)

A frosty sunset is seen through icicles in Peremilovo village, 65 km (40,6 miles) north of Moscow, Russia, Sunday, December 16, 2018. Temperatures in the Moscow region on Sunday dropped to –12 degree Celsius (10 Fahrenheit). (Photo by Alexander Zemlianichenko/AP Photo)

In this June 6, 1966 file photo, civil rights activist James Meredith pulls himself across Highway 51 after being shot in Hernando, Miss. Meredith, who defied segregation to enroll at the University of Mississippi in 1962, completed the march from Memphis, Tenn., to Jackson, Miss., after being treated for his wounds. (Photo by Jack Thornell/AP Photo)

People hold umbrellas as they walk past a flooded street in Taiyuan, Shanxi Province, China, July 19, 2016. (Photo by Reuters/China Daily)

Police haul a youth to the paddy wagon as an undetermined number of arrest were made in downtown Atlanta, Georgia, February 25, 1971, as police moved in to disperse black youths after windows were broken and rocks and fruit thrown in what officers called “a major disturbance”. (Photo by Charles Kelly/AP Photo)