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)

A motorway bridge crosses the icy Hunhe River in Shenyang, China on December 12, 2019. (Photo by Costfoto/Barcroft Media)

Indian people bang utensils and clap from the balconies of a residential building in Mumbai, India, 22 March 2020. Prime Minister Narendra Modi asks citizens to impose self-curfew to fight Coronavirus COVID-19 and also ask them to clap, bang the bells and utensils at 5pm Indian time to mark of respect and to thank the medical staff and others working 24 hours, during Covid-19 outbreak to keeping the Indians safe. (Photo by Divyakant Solanki/EPA/EFE)

Police officers display their AI-powered smart glasses in Luoyang, Henan province, China on April 4, 2018. (Photo by Reuters/China Stringer Network)

North Korean youngsters sing and play accordions to entertain foreign visitors including United Nations Secretary General Kurt Waldheim, who visited Pyongyang, May 4, 1979. Visitors report music education in North Korea begins at an early age and is taken seriously by children and adults. (Photo by Peter Arnett/AP Photo)

Three Chinese soldiers at the time of a civil war in China. (Photo by General Photographic Agency/Getty Images). 1922

Stuart Craig of Washington tries out a Sig Sauer 1911 model Scorpion pistol at the Sig Sauer booth at the National Shooting Sports Foundation's 34th annual Shooting, Hunting, Outdoor Trade (SHOT) Show at the Sands Expo and Convention Center January 17, 2012 in Las Vegas, Nevada. The SHOT Show is the largest annual gathering of shooting professionals with more than 1,600 exhibitors and 30,000 attendees expected. (Photo by Ethan Miller/Getty Images)

A girl collects drinking water at Dala river outside Yangon, Myanmar March 3, 2016. Some 650 million people, or one in 10 of the world's population, have no access to safe water, putting them at risk of infectious diseases and premature death. Dirty water and poor sanitation can cause severe diarrhoeal diseases in children, killing 900 under-five a day across the world, according to United Nations estimates. (Photo by Soe Zeya Tun/Reuters)