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)

In this Tuesday, May 3, 2016 photo, Madeley Vasquez, 16, breast feeds her one-year-old son Joangel as she waits in line outside a supermarket to buy food in Caracas, Venezuela. Vasquez once ran down the block to avoid getting caught up in a knife fight that broke out when a woman was accused of cutting the line. (Photo by Ariana Cubillos/AP Photo)

(L-R) Jade Chapman, Maryam Maquillage, Mariah Carey, Laura Lee and Arika Sato attend M.A.C Cosmetics Mariah Carey Beauty Icon Launch at Baccarat Hotel on December 3, 2016 in New York City. (Photo by Theo Wargo/Getty Images for M.A.C)

Local villagers ride a local coal powered steam train on March 27, 2015 at a station in the town of Shixi , Sichuan Province, in Southern China. While China boasts the world's most extensive high-speed rail infrastructure with over 16,000 kilometers of track, the Shixi-Bagou railway is still a primary connection for local villagers between towns and is kept alive by tourist cars carrying passengers for ten times the price. The rail line came into service in the late 1950s and the train was initially used to transport coal from a now-shuttered mine before passenger carriages were added. (Photo by Kevin Frayer/Getty Images)

Young men play basketball on an improvised court wedged between a construction site and the shells of once grand colonial homes in Havana, July 20, 2015. As much as the young in Cuba welcome political opening and economic reform, such changes are unlikely to filter down to their lives anytime soon. (Photo by Meridith Kohut/The New York Times)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Demonstrators hold masks depicting Colombian citizen Mile Virginia, who was murdered along with photojournalist Ruben Espinosa and three other women, during a protest in Mexico City, August 16, 2015. Espinosa, a prominent Mexican news photographer was among five people found dead in a middle-class neighborhood of the capital on July 31, 2015. Espinosa, who worked for the weekly magazine Proceso and the photo agency Cuartoscuro, had sought shelter in Mexico City earlier this summer saying he had been followed and threatened in the eastern state of Veracruz. (Photo by Tomas Bravo/Reuters)

Model Lily Donaldson flashes the peace sign as she leaves Victoria's Secret Fashion Show China casting in New York City on August 22, 2017. (Photo by Christopher Peterson/Splash News and Pictures)