People smear black ash with hands onto each other to wish for good luck and fortune during a traditional festival of the Yi ethnic minority in Qiubei County, Yunnan province, China July 18, 2017. (Photo by Ren Dong/Reuters/CNS)

A woman carries her child as she watches Mount Sinabung volcano spewing thick volcanic ash, as seen from Karo on July 21, 2017. Sinabung roared back to life in 2010 for the first time in 400 years, after another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Gatha Ginting/AFP Photo)

A performer dances at a housing exhibition in Wuhan, Hubei province, China, September 27, 2015. (Photo by Reuters/Stringer)

Residents with faces covered in ash ride on a motorcycle as Mount Sinabung volcano erupts, in Sukandebi village in Karo Regency, Indonesia's North Sumatra province, Indonesia June 13, 2015, in this photo taken by Antara Foto. (Photo by Rony Muharrman/Reuters/Antara Foto)

A man covered with dust sits on a street following a reported air strike by Syrian government forces in the rebel-held neighbourhood of Sukkari in the northern city of Aleppo on May 30, 2016. (Photo by Baraa Al-Halabi/AFP Photo)

A woman sports a rainbow painted hand at the annual PrideFest celebration at Civic Center Park in Denver, Colorado June 18, 2016. (Photo by Andy Cross/The Denver Post)

A brown bear waits for food at the zoo in Madrid, Spain on July 30, 2016. (Photo by Jorge Sanz/Pacific Press/SIPA Press/Rex Features/Shutterstock)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)