The sun rises through the thick fog that covers the city of Frankfurt, Germany, Friday, November 12, 2021. (Photo by Michael Probst/AP Photo)

Commuters by with the buildings of the banking district in background in Frankfurt, Germany, Thursday, February 6, 2020. (Photo by Michael Probst/AP Photo)

Police officers check documents of a man in central Moscow, Russia, Sunday, June 25, 2023. (Photo by Dmitri Lovetsky/AP Photo)

People take part in the Burning of the Clavie fire festival in Burghead, Moray, UK on Saturday, January 11, 2025. Burghead welcomes in the New Year twice each year, on both January 11th and the more traditional January 1st. (Photo by Jane Barlow/PA Images via Getty Images)

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

A woman walks in the stairs of the Hotel Martinez in Cannes as the French Riviera prepares for the 2021 edition of the Cannes Film Festival which will take place next July, in France, June 3, 2021. (Photo by Eric Gaillard/Reuters)

Dawn at Blyth beach huts in Northumberland, with the prospect of warm weather over the coming weekend on Friday, October 8, 2021. (Photo by Owen Humphreys/PA Images via Getty Images)

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)