A woman wearing a scarf to cover her face looks on as she waits for a passenger bus on a smoggy morning in New Delhi, India, November 8, 2017. The Great Smog of Delhi is an ongoing severe air-pollution event in New Delhi and adjoining areas in the National Capital Territory of India, in November 2017. Air pollution at this time peaked on both PM 2.5 and PM 10 levels. It has been reported as one of the worst levels of air quality in Delhi since 1999. (Photo by Saumya Khandelwal/Reuters)

Employee Jenny Forgie works on an orchid display at Kew Gardens in London, Thursday, February 8, 2018. The 23rd annual Orchid Festival is the first one with a Thailand theme, 66 volunteers worked on the 6,950 exhibited orchids. The festival is open from Feb. 10, 2018 until March 11, 2018. (Photo by Frank Augstein/AP Photo)

Patrick Fellows #21, Allan McShane #26, Carson Edwardson #8 and Shaun Bily #23 of the Erie Otters sit on the bench during the first period of an OHL game against the Niagara IceDogs at the Meridian Centre on October 6, 2016 in St Catharines, Ontario, Canada. (Photo by Vaughn Ridley/Getty Images)

Dressers make last minute adjustments to the costumes of dancers performing as horses during a press preview of American artist Nick Cave's first major work shown in Australia, entitled HEARD.SYD in Sydney, November 8, 2016. Over several days the live art performance will feature 30 “horses” dancing to live percussion beats in suits made from coloured raffia plant fibres. (Photo by Jason Reed/Reuters)

An Israeli soldier from the Nahal Infantry Brigade runs through smoke released from a smoke grenade during an urban warfare drill near an abandoned hotel in Arad, southern Israel February 8, 2017. (Photo by Amir Cohen/Reuters)

A woman covers her face as a fire burns in the middle of town during an anti-G20 protest on July 7, 2017 in Hamburg, Germany. Authorities are braced for large-scale and disruptive protests as Leaders of the G20 group of nations arrive in Hamburg for the July 7-8 G20 summit. (Photo by Leon Neal/Getty Images)

South Korea's Amry Special Warfare Command (SWC) soldiers aim their machine guns in a frozen river during a winter exercise in Pyeongchang, South Korea, Thursday, January 8, 2015. About 200 SWC soldiers participated in this routine two-week winter drill. (Photo by Ahn Young-joon/AP Photo)

Sakia Corona, 8, (C) takes part in a rehearsal of the Contemporary Haitian Dance in a communal center in downtown Havana January 30, 2015. Nearly 25 people, from the Haitian Contemporary Dance Company Petit Fey or Small Leaf, in Haitian Creole, rehearse a play called Papa Guede for future presentations in Havana. (Photo by Alexandre Meneghini/Reuters)