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)

A visitor stands in front of a portrait taken by artist Bruce Gilden at the “Masters of Photography” exhibition at the Photokina trade fair in Cologne on September 20, 2016. The fair for the photographic and imaging sector, that is running from September 20 to 25, 2016, presents products from image capture, image processing and storage to image output. Photokina also includes a program of events with congresses, workshops, symposiums and photography exhibitions. (Photo by Patrik Stollarz/AFP Photo)

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)

A view of one of the stands during the inauguration of the Integrated Systems Europe (ISE) fair, the largest audiovisual show in the world, in Barcelona city, Catalonia, north-eastern Spain, 31 January 2023. The event runs until 03 February, gathers 68,000 registered attendees and 1,055 exhibiting companies. (Photo by Quique Garcia/EPA)

This photo taken on October 23, 2022 shows a soap bubble reflecting the Namsan Seoul Tower at Namsan Park in Seoul, South Korea. (Photo by Xinhua News Agency/Rex Features/Shutterstock)

A model showcases designs on the catwalk by Manning Cartell during A Review of Australian Fashion Week show as part of Mercedes Benz Fashion Festival Sydney 2011 at Sydney Town Hall on August 27, 2011 in Sydney, Australia. (Photo by Don Arnold/Getty Images)