A woman wears a face mask in the part of the city near neighbourhoods known for burning coal for heating in Ulaanbaatar, Mongolia January 26, 2017. Not many people in Ulaanbaatar wear masks to protect themselves against pollution. (Photo by B. Rentsendorj/Reuters)

Pilgrims lift up their dresses as they cross the Quema river during the annual El Rocio pilgrimage in Villamanrique, near Sevilla on June 1, 2017. El Rocio pilgrimage is the largest in Spain with hundreds of thousands of devotees wearing traditional outfits converging in a burst of colour as they make their way on horseback and decorated carriages across the Andalusian countryside. (Photo by Cristina Quicler/AFP Photo)

In this image made available by France's Marine Nationale, the cargo ship TK Bremen sits stranded on a beach near Erdeven, France, on December 16, 2011, spilled fuel oil fouling the water. (AP Photo/Mael Prigent, Marine Nationale)

A man representing the devil leaps over babies during the festival of El Colacho on June 10, 2012 in Castrillo de Murcia near Burgos, Spain. The festival, held on the first Sunday after Corpus Cristi, represents the devil taking away original sin from the newly born babies by leaping over them. (Photo by Denis Doyle)

A large Pacific sideband snail slowly crosses a rain wet road in rural Douglas County, Oregon near Elkton on Sunday, December 2, 2012. The moisture loving snail should be very content with the recent heavy rains in southwestern Oregon and northern California. (Photo by Robin Loznak)

New York Police Department tactical police officers stand guard near the New York Stock Exchange on September 9, 2011 in New York City. Officials are stepping up security in New York and Washington D.C. a day after U.S. officials received a credible but unconfirmed terror threat to utilize car bombs on bridges or tunnels in New York or Washington. (Photo by Justin Sullivan/Getty Images)

A boat paddles behind a fence near a plane sitting on the flooded tarmack of the closed Don Muang airport November 3, 2011 in Bangkok,Thailand. The airport was used as a domestic terminal and was formerly the International airport. Thailand is experiencing the worst flooding in over 50 years and has affected more than nine million people. Over 400 people have died in flood-related incidents since late July according to the Department of Disaster Prevention and Mitigation. (Photo by Paula Bronstein/Getty Images)

An arrow-head discovered in 2006 by Archaeologists of the University of Cambridge Archaeological Unit, is displayed by one of the team uncovering Bronze Age wooden houses, preserved in silt, from a quarry near Peterborough, Britain, January 12, 2016. Archaeologists said on Tuesday they had discovered what were believed to be the best-preserved Bronze Age dwellings ever found in Britain, providing an extraordinary insight into prehistoric life from 3,000 years ago. (Photo by Peter Nicholls/Reuters)