People walk during a polluted day in Shenyang, Liaoning province, March 31, 2016. (Photo by Reuters/Stringer)

A couple watches the sunset over a sea of fog covering the Geneva Lake from Chardonne, Switzerland, 28 December 2015. (Photo by Jean-Christophe Bott/EPA)

Entomologist Anna Platoni wears a hat made of tropical flowers made by florist Emma Reynolds with a Blue Morpho butterfly on her cheek to mark the opening of Butterflies in the Glasshouse at RHS Garden Wisley, south of London, on Janurary 15, 2016. (Photo by Luke MacGregor/PA Wire/RHS)

People walk passed sculptures by Chinese artist Minjun Yue on a street outside a museum in Beijing, China on July 5, 2018. (Photo by Nicolas Asfouri/AFP Photo)

A high temperature alerts were issued as a record-setting summer heat wave continued to bake most parts of south China. (Reuters)

A man rides his loaded tricycle next to three schoolgirls in Shanghai on December 11, 2015. (Photo by Johannes Eisele/AFP Photo)

A boy and a woman run across a railway track as a train approaches in Chengdu, Sichuan province, China, October 8, 2015. Many residents disregard sign prohibiting this kind of illegal crossing and choose to do so to save time, local media reported. (Photo by Hao Fei/Reuters/Western China Metropolis Daily)

A Sikh warrior, wearing a huge turban attends the annual fair of “Hola Mohalla” in Anandpur Sahib, in the northern Indian state of Punjab, Monday, March 17, 2014. Believers from various parts of northern India collect at the religious fair to celebrate the festival of Holi in a tradition set by the tenth Sikh guru Guru Gobind Singh in the seventeenth century. Nihangs, or Sikh warriors, display their martial skills and attire during the fair, believed to be maintained in the exact tradition as set by the Guru. (Photo by Altaf Qadri/AP Photo)