A woman wearing a mask walk in a street in a Yonghegong Lama temple compound seen shrouded in smog in Beijing, China, 30 November 2015. Beijing issued an orange alert for heavy smog 30 November, the highest level this year. Authorities in the Chinese capital warned of 'severe pollution' and advised the capital's 20 million inhabitants to stay indoors. (Photo by How Hwee Young/EPA)

Palestinian children warm themselves by a fire on a stormy day at Shati (beach) refugee camp in Gaza City January 18, 2016. (Photo by Mohammed Salem/Reuters)

People stroll alongside one of the hills of the Tio Pio park in Madrid, Monday, January 25, 2016. The park is a high viewpoint frequented mostly by locals due to its view of the Spanish capital skyline. (Photo by Francisco Seco/AP Photo)

A Buddhist monk lights a candle at Wat Phra Dhammakaya during a ceremony on Makha Bucha Day in Pathum Thani province, north of Bangkok February 22, 2016. Makha Bucha Day honours Buddha and his teachings, and falls on the full moon day of the third lunar month. (Photo by Jorge Silva/Reuters)

Street vendors hold campaign posters for presidential candidate Patrice Talon ahead of the second round of Benin's presidential election on Sunday in Cotonou, Benin, March 18, 2016. (Photo by Charles Placide Tossou/Reuters)

In this photo taken on Sunday, September 4, 2016, a Kyrgyz boy holds a golden eagle during the second World Nomad Games at Issyk Kul lake in Cholpon-Ata, Kyrgyzstan. The Games, which opened on Saturday on a picturesque mountain plain in eastern Kyrgyzstan, bring together athletes from 40 countries including Russia and the United States where nomadic traditions are strong. (Photo by Vladimir Voronin/AP Photo)

American soldiers with the 173rd Airborne Brigade Battle Company, on a battalion-wide mission in the Korengal Valley, looking for caves, weapons caches and known Taliban leaders, 2007. Tanner Stichter tends to Spc. Carl Vandeberge in the bushes moments after Vandeberge was shot in the stomach during a Taliban ambush, which killed one soldier and wounded two others. (Photo by Lynsey Addario)

Pakistani youths cool off in a stream during hot weather on the outskirts of Islamabad on April 29, 2016. Pakistan's Meteorological Department has forecast hot and dry weather in most parts of the country with the highest temperatures recorded at 41 celsius in the southern Sindh province. (Photo by Aamir Qureshi/AFP Photo)