John Klatt and the Air National Guard MXS (right) and Mike Wiskus and the Lucas Oil Pitts take to the skies at the Memphis Airshow, on Sat., September 26, 2016 in Millington, Tenn. (Photo by Brandon Dill/Invision for John Klatt Airshows, Inc./AP Images)

The Royal Air Force aerobatic team, the Red Arrows, perform during The Royal International Air Tattoo at the RAF in Fairford July 11, 2014. (Photo by Stefan Wermuth/Reuters)

An Aerial view Admiralty Arch at the top of The Mall on July 26, 2011 in London, England. (Photo by Tom Shaw/Getty Images)

Air conditioners, more than 500 in total, hang on the wall of an office building on August 15, 2011 in Fuzhou, Fujiang Province of China. This 25-story office building was built with no central air conditioner system, each office has it own individual unit installed on the exterior creating this wall of air conditioners. (Photo by ChinaFotoPress/Getty Images)

A Saudi soldier fires a mortar towards Houthi movement position, at the Saudi border with Yemen April 21, 2015. (Photo by Reuters/Stringer)

Wizz Air's Airbus A-321 flying along the Danibe river during an air show in Budapest, Hungary, May 1, 2016. (Photo by Laszlo Balogh/Reuters)

The Mil Mi-28 N military helicopter is seen at the MAKS 2019 air show in Zhukovsky, outside Moscow, Russia, August 27, 2019. (Photo by Maxim Shemetov/Reuters)

Pedestrians cover their face as they walk along the dusty road in Kathmandu, Nepal February 27, 2017. Nepal has forced 2,500 old vehicles off roads in its capital city of Kathmandu, part of a fight against alarming air pollution levels that have hit nine times World Health Organisation (WHO) limits. Air pollution has been a chronic problem in rapidly growing Kathmandu, which sits in a Himalayan valley and is home to more than 3mn people. (Photo by Navesh Chitrakar/Reuters)