Competitors take part in the annual Mud Madness event at Foymore Lodge on April 22, 2018 in Portadown, Northern Ireland. The adult version of the event includes two laps of an 8km course through 25 obstacles while the kids event is run over 2kms. The race is in it's eleventh year and is sponsored by McVities Jaffa Cakes and event charity partner Marie Curie together with other numerous charities and fundraising groups. (Photo by Charles McQuillan/Getty Images)

A Chinese man wears a mask to protect against pollution as he waits at a red light while commuting to work in heavy smog on December 8, 2015 in Beijing, China. The Beijing government issued a 'red alert' for the first time since new standards were introduced earlier this year as the city and many parts of northern China were shrouded in heavy pollution. Levels of PM 2.5, considered the most hazardous, crossed 400 units in Beijing, lower than last week, but still nearly 20 times the acceptable standard set by the World Health Organization. The governments of more than 190 countries are meeting in Paris to set targets on reducing carbon emissions in an attempt to forge a new global agreement on climate change. (Photo by Kevin Frayer/Getty Images)

A hot air ball balloon floats past while people stand in line to climb the Pyramid of the Sun and welcome the spring equinox in the pre-hispanic city of Teotihuacan, on the outskirts of Mexico City, Mexico, March 20, 2016. Spring equinox in Teotihuacán is an annual event which takes place around the 20th and 21st of March at the pre-Hispanic site of Teotihuacán, Mexico. This event is mirrored by other similar events in other pre-Hispanic sites such as Chichén Itzá and Malinalco, Mexico State. (Photo by Edgard Garrido/Reuters)

A cosplay enthusiast poses as Serasu Vikutoria of the Hellsing anime series during the “Anime Friends” annual event in Sao Paulo July 19, 2015. Anime Friends is one of Brazil's biggest events related to anime, manga and Japanese culture. (Photo by Nacho Doce/Reuters)

A man smashes an apple with a sword placed on the head of a man wearing a knave costume during the Easter knight event on April 21, 2014 in Berlin. The easter knight event delivers an insight into medieval lifestyle. (Photo by Rainer Jensen/AFP Photo/DPA)

Hugo Belleri (L), a three-year-old boy and the youngest Gilles of Binche, takes part in the parade of Young Gilles of Binche during the carnival event in Binche February 17, 2015. The Binche carnival, a UNESCO World Heritage event, is the biggest and the liveliest annual event in Belgium. Up to 1,000 Gilles parade in the city centre of Binche, wearing a red, yellow and black medieval costume hung with bells and decorated with fluffy lace at the neck, wrists and ankles. (Photo by Yves Herman/Reuters)

Participants demonstrate for the media before the role play event at Czocha Castle in Sucha, west southern Poland April 9, 2015. Harry Potter enthusiasts from all over the world are attending a four-day live action role play event at the medieval castle made into a close imitation of the “College of Wizardry”. (Photo by Kacper Pempel/Reuters)

Comic Con fans in costume arrive for the 1st day of the 2018 New York Comic-Con at the Jacob Javits Center on October 4, 2018. The four-day event which runs October 4-7 is the largest pop culture event on the East Coast. (Photo by Timothy A. Clary/AFP Photo)