s*x workers, wearing decorative skull masks, march through the streets in downtown Mexico City, Friday, October 28, 2016. The women march with candles to an altar dedicated to their departed colleagues, many who died violently at the hands of their customers. This annual procession, tied to the Day of the Dead festivities, has taken place for more than 20 years. (Photo by Eduardo Verdugo/AP Photo)

A citizen rides in smog on December 20, 2016 in Jinan, Shandong Province of China. Air quality index (AQI) readings exceeded 400 and some schools have suspended classes in Jinan. (Photo by VCG/VCG via Getty Images)

A general view of the residential area is pictured during dusk at Jodhpur in Rajasthan, April 5, 2015. Jodhpur, also known as the blue city in the desert Indian state of Rajasthan, which residents say originally, was used to show where the highest caste of priestly Hindus live, who wanted to set them apart from the rest of the population. Later the rest of the population followed suit. Another reason for the city to be blue is to keep the buildings cool during the summers, local residents said. (Photo by Adnan Abidi/Reuters)

A woman waters the plants outside her house in an alley at a slum in Mumbai October 28, 2014. (Photo by Danish Siddiqui/Reuters)

Yakutsk, a remote city in Eastern Siberia along the Lena River, is the coldest city in the world. Located 1840 km away from Irkoustk and 5000 km away from Moscow, this city founded in 1632 by the Cossacks imposes upon its inhabitants an extreme way of life. And yet, despite particularly harsh conditions, Yakutsk boasts a population of 270,000, or a quarter of the entire population of Siberia. No other place on the planet experiences the temperature extreme found here: in winter, the temperatures regularly fall to minus 40° (the coldest temperature recorded was –64°C) and in summer often reaches temperatures above 30°C. Photo: January 2013. A scene in Yakutsk, Siberia, the coldest city in the world. (Photo by Steeve Iuncker/Agence VU)

A girl pours water over a dog to cool it down, in the rebel held besieged town of Douma, eastern Damascus suburb of Ghouta, Syria, June 23, 2016. (Photo by Bassam Khabieh/Reuters)