A general view shows smoke and volcanic ashes billowing from volcano Cotopaxi in Pedregal, Ecuador, late 07 October 2015. (Photo by Jose Jacome/EPA)

Palestinian girls take part in a ballet dancing course, run by the Al-Qattan Center for Children, in Gaza City November 25, 2015. (Photo by Suhaib Salem/Reuters)

Artist Kong Ning wears a wedding dress made from respirators to highlight concerns about air quality and pollution in Beijing, China on December 1, 2015. (Photo by Luo Xiaoguang/Xinhua Press/Corbis)

People take part in the "Bison Race" winter extreme run competition in Zhodino, Belarus, December 5, 2015. (Photo by Vasily Fedosenko/Reuters)

A man has an egg smashed on his head to raise money for charity during the World Egg Throwing Championships and Vintage Day in Swaton, Britain June 28, 2015. (Photo by Darren Staples/Reuters)

Samburu tribesmen stand during the Maralal Camel Derby, Kenya, August 15, 2015. Maralal, a small, arid town about an eight-hour drive north of the Kenyan capital Nairobi, holds an annual camel festival, bringing together members of the Samburu, Turkana and Pokot semi-nomadic cattle-herding tribes. (Photo by Goran Tomasevic/Reuters)

Erica Bougard of the U.S. competes in the high jump event of the women's heptathlon during the 15th IAAF World Championships at the National Stadium in Beijing, China, August 22, 2015. (Photo by Fabrizio Bensch/Reuters)

A participant wrestles with a pig in the “greased pig contest” at the Festival du Cochon (Pig Festival) in Sainte-Perpetue, Quebec August 8, 2015. (Photo by Christinne Muschi/Reuters)