A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

First responders work at the site of a deadly bus crash, in Guatemala City, Guatemala, on February 10, 2025. (Photo by Josue Decavele/Reuters)

Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)

In this October 7, 2018 photo waitress dance in the Hofbraeu tent after the closing of the Oktoberfest beer festival in Munich, southern Germany, which ran from September 22 through October 7, 2018. (Photo by Felix Hoerhager/AP Photo)

Women atop a boat take a group photo as the U.S. Navy’s Flight Demonstration Squadron’s Blue Angels perform in the skies over Annapolis, Maryland, on May 22, 2024. (Photo by Kevin Lamarque/Reuters)

A participant, riding a horse and dressed as a knight, presents flowers to women during an event marking Valentine's Day in central Moscow, Russia, February 14, 2016. (Photo by Maxim Zmeyev/Reuters)

A man rides his loaded tricycle next to three schoolgirls in Shanghai on December 11, 2015. (Photo by Johannes Eisele/AFP Photo)

Army soldiers prepare a military elephant for the parade during a rehearsal for Sri Lanka's 68th Independence day celebrations in Colombo, February 2, 2016. (Photo by Dinuka Liyanawatte/Reuters)