A ballet dancer practices in the sunshine at the Southbank skatepark in London on Monday, September 17, 2018, as Storm Helene is due to bring unseasonably warm weather in London and the south east, as the low pressure draws up warm air from the south. Forecasters have downgraded warnings that Helene could pose a risk to life when it hits this week – but warned coastal communities to stay vigilant. (Photo by Kirsty O'Connor/PA Wire)

Pedestrians wear masks as smoke and haze from bushfires in New South Wales blankets the CBD in Sydney, Australia, 10 December 2019. The New South Wales environment department says visibility across east and southwest Sydney was at a “hazardous” level on Tuesday morning, while air quality was poor in southwest Sydney and hazardous in northwest Sydney. (Photo by Steven Saphore/EPA/EFE)

Aldi SugandaRizal (2 years-old) smoking a cigarette while playing at the family home in Sekayu district, South Sumatera, Indonesia on May 23, 2010. (Photo by Ardiles Rante/Barcroft Media)

Boys play with a ball in front of oilfields burned by Islamic State fighters in Qayyara, south of Mosul, Iraq November 23, 2016. (Photo by Goran Tomasevic/Reuters)

Members of the Iraqi Army fire towards Islamic State militant positions at the south of Mosul, Iraq December 10, 2016. (Photo by Alaa Al-Marjani/Reuters)

A one and a half months old baby elephant stands close to its mother at Chitwan National Park in Chitwan, south of Kathmandu December 30, 2014. (Photo by Navesh Chitrakar/Reuters)

A person poses on the track during a fashion competition at the Durban July horse racing event in Durban, South Africa July 1, 2017. (Photo by Rogan Ward/Reuters)

Participants play with water guns during the Sinchon Water Gun Festival in Seoul, South Korea, July 9, 2016. (Photo by Kim Hong-Ji/Reuters)