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)

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

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)

MY Raven, a former steamer now converted to diesel, cruises across Ullswater from Glenridding to Pooley Bridge in Cumbria, UK on October 25, 2024. (Photo by Andrew McCaren/London News Pictures)

Sepak Takraw, ISTAF Super Series Finals Thailand 2014/2015, Nakhon Pathom Municipal Gymnasium, Huyjorake Maung, Nakonprathom, Thailand on October 20, 2015: Thailand's Sudaporn Palang in action during the group stage. (Photo by Asia Sports Ventures/Action Images via Reuters)

A woman smokes a mask bong on the final day of Hempfest, Seattle's annual gathering to promote the legalization of marijuana, on August 17, 2014. (Photo by Jordan Stead/Seattlepi.com)

In this picture made available Thursday July 11, 2013 a zoo-keeper presents three of twelve ferret babies at Eekholt Zoo in Grossenaspe, Germany, Wednesday July 10, 2013. The ferret babies were born May 25, 2013. (Photo by Markus Scholz/AP Photo/Dpa)