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 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)

In this Sunday, April 6, 2014 photo, Valery Palma prepares to blow out the candle on a birthday cake for her one-year-old dachshund Camila, at Camila's birthday party in Mexico City. Palma, who has two dogs, spent $300 on the birthday party for 11 canines and 16 people, complete with cake, presents and snacks, at a dog hotel featuring a gym and massage and aromatherapy services. (Photo by Rebecca Blackwell/AP Photo)

Miniscule larvae carve winding tunnels as they eat through small leaves in a small forest near the town of Velbert in western Germany in July 2022. The hungry green sawfly larvae measure just three millimetres in length and are difficult to spot on the leaves of the beech tree unless up close. (Photo by Christian Brockes/Solent News)

The Forth Bridge is engulfed by mist on one of the coldest days of the year, on December 12, 2022, in Edinburgh, Scotland. (Photo by Ken Jack/Getty Images)

A motoring enthusiast takes part in the “Race The Waves” classic car and motorcycle meet at the beach in Bridlington, Britain, on May 12, 2024. (Photo by Lee Smith/Reuters)