Tourists crowd a water park in Wuhan city, central China's Hubei province on July 15, 2017. Days of heat wave drove many citizens to the water park for fun and coolness. Nanchang has become the new four “furnace cities” in China according to a ranking of the hottest cities released by the China Meteorological Administration on July 9. (Photo by Imaginechina/Rex Features/Shutterstock)

People walk on the “Europabruecke” bridge, the world's longest pedestrian suspension bridge with a length of 494m, after the official inauguration of the construction in Randa, Switzerland, 29 July 2017. The bridge is situated on the Europaweg that connects the villages of Zermatt and Graechen. (Photo by Valentin Flauraud/EPA)

A woman takes part in the Watermelon Games at the 55th annual California Watermelon festival in Los Angeles, California on July 29, 2017. The day has become a tradition because watermelons have long been the prized crop of the eastern San Fernando foothills. (Photo by Xinhua News Agency/Rex Features/Shutterstock)

Bicycles of various bike-sharing services are seen at an urban village in smog during a polluted day in Shanghai, 2017. Rapid expansion of shared bicycle companies across China has led to massive piles of abandoned bikes as supply outstrips demand. (Photo by Aly Song/Reuters)

A model presents a creation from fashion label Maison Lejaby during the Festival of Young Fashion Designers, an event held in tribute to Azzedine Alaia, a Franco-Tunisian fashion designer who died in November 2017; in Tunis, Tunisia, 04 May 2018. (Photo by Mohamed Messara/EPA/EFE)

Vehicles pass through the heavy fog and air pollution that cover Skopje valley in the early morning, in Skopje, The Former Yugoslav Republic of Macedonia, 14 December 2017. According to media reports, Skopje is considered one of the most polluted cities in the world. (Photo by Georgi Licovski/EPA/EFE)

People enjoy skating at the open air Christmas ice rink on the first floor of the Eiffel Tower after its reopening on December 19, 2016 in Paris The ice rink of about 200 square metres and on the first floor of the tower (57 metres above the ground) is open to the public until February 19, 2017. (Photo by Joel Saget/AFP Photo)

Soldiers march to mark the Armed Forces Day and commemorate the landing of the yacht Granma, which brought the Castro brothers, Ernesto “Che” Guevara and others from Mexico to Cuba to start the revolution in 1959, in Havana, Cuba, January 2, 2017. (Photo by Alexandre Meneghini/Reuters)