Local residents crowd a swimming pool during a hot weather in Suining, Sichuan province, 27 July 2008. (Photo by Reuters/Stringer)

A women wearing a mask to protect from extreme smog visits the Tiananmen Gate in Beijing December 8, 2015 as China's capital issues its first ever "red alert" for pollution. (Photo by Damir Sagolj/Reuters)

Participants run through the streets of the Back Bay during the 16th annual Santa Speedo Run in Boston, Massachusetts, December 12, 2015. (Photo by Brian Snyder/Reuters)

Labourers load a three-wheeled vehicle onto the back of a van at the Mercato market in Addis Ababa October 9, 2015. Addis Ababa's “Mercato” – Italian for “market” – is reputedly the biggest open-air market in Africa, lying in the west of the capital. (Photo by Tiksa Negeri/Reuters)

Talbot Lago T26 Grand sport SWB Saoutichik is displayed for auction during the Retromobile show in Paris, Tuesday, February 3, 2015. 60 rusting motors, which include a vintage Ferrari California Spider, a Bugatti and a very rare Maserati, were found gathering dust and hidden under piles of newspapers in garages and outbuildings at a property in France. The cars were collected from the 1950s to the 1970s by entrepreneur Roger Baillon, who dreamt of restoring them to their former glory and displaying them in a museum, but, his plans were dashed as his business struggled, forcing the sale of about 50 vehicles, to be auctioned off on Feb. 6. (Photo by Jacques Brinon/AP Photo)

Young Ukrainians dance at nightclub House of Meteorologists, May 23, 2014. Sunday's upcoming election in Ukraine has not only exposed the divide between east and west, but between old and young. Unlike their elders, younger people have no memory of Soviet life, and most see themselves as Ukrainian. (Photo by Evelyn Hockstein/The Washington Post)

Alexo Carmona, 2, looks at Coco, a two-year-old pony, in downtown Havana, in this March 6, 2015 file photo. Nearly a quarter of a million people follow the Reuters Instagram account – and it's still growing fast. To mark the mid-point of 2015, Reuters has compiled the twenty most-liked pictures so far. This picture was 20th most popular. (Photo by Alexandre Meneghini/Reuters)

Balloons are inflated at the Bristol International balloon fiesta in south west England August 6, 2015. Now in its 37th year, the Bristol International Balloon Fiesta is Europe's largest annual hot air balloon event in the city that is seen by many balloonists as the home of modern ballooning. (Photo by Toby Melville/Reuters)