Students play in their school yard on the first day of the new school term at a primary school in Baghdad, October 18, 2015. (Photo by Ahmed Saad/Reuters)

Revellers take part in a zombie parade to celebrate Halloween in Vina del Mar, October 31, 2015. (Photo by Rodrigo Garrido/Reuters)

An Egyptian passenger sits on the locomotive of a train as it leaves Cairo train station in Egypt, Wednesday, October 14, 2015. (Photo by Amr Nabil/AP Photo)

Participants wearing masks during a hazy day at the Beijing International Marathon in front of Tiananmen Square, in Beijing, October 19, 2014. (Photo by Reuters/Stringer)

People dance in a park on a foggy day in Huai'an, Jiangsu province, China October 10, 2017. (Photo by Reuters/China Stringer Network)

Revelers march during the Greenwich Village Halloween Parade, Tuesday, October 31, 2017, in New York. (Photo by Andres Kudacki/AP Photo)

People wearing costumes walk during Halloween in Sierra Madre, California, U.S., October 31, 2017. (Photo by Mario Anzuoni/Reuters)

A woman crosses the street on a foggy morning in Frankfurt, Germany, Friday, October 29, 2021. (Photo by Michael Probst/AP Photo)