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)

Participants take part in the Mud Day race, a 13km obstacle course, on March 24, 2017 in the Israeli Mediterranean coastal city of Tel Aviv. (Photo by Jack Guez/AFP Photo)

A model wears a floral headdress at the Royal Horticultural Society's Chelsea Flower show in London, Britain, May 22, 2017. The prestigious Chelsea Flower Show, held annually since 1913 in the Royal Hospital Chelsea grounds, is open to the public from the 23rd to the 27th of May, 2017. (Photo by Dylan Martinez/Reuters)

Jazmin, 6, sister of Jose Luis, receives Isoniazid Preventive Therapy in Carabayllo in Lima, Peru July 14, 2016. At least 30,000 Peruvians are infected with tuberculosis, an ancient disease that killed 1.8 million globally last year, more than AIDS-related and malaria deaths combined. Partners in Health, a Boston-based non-profit that works with Peru's health ministry, offers a simple solution. It trains community volunteers to tend to tuberculosis sufferers in their homes – ensuring patients take medicine daily and helping them navigate the public health bureaucracy. (Photo by Mariana Bazo/Reuters)

Principle Ballet Dancer, Ekaterina Bulgutova, of the Russian State Ballet, with the Nutcracker part of Christmas Ballet Season in Cardiff which starts at St Davids Hall on December 20, 2016 in Cardiff, England. (Photo by Kiran Ridley/Barcroft Images)

Fans dressed as Darth Vader and Chewbacca take a boat trip to the Skelligs on May 4, 2018 in Portmagee, Ireland. The first ever Star Wars festival is taking place against the backdrop of the famous Skellig Michael island which was used extensively in Episode VII and Episode VIII of the popular science fiction saga. The small fishing village of Portmagee, which is closest to the location, has seen a boom in tourism following the latest films. The vilage will host a Star Wars drive-in and a Star Wars themed Irish dancing competition over the weekend. (Photo by Charles McQuillan/Getty Images)

A woman carries a floral design handbag at the RHS Chelsea Flower Show in London, Britain on May 21, 2018. The annual show of floral art, timed to coincide with the RHS Chelsea Flower Show nearby, sees over sixty shops, restaurants and local businesses compete for prizes, with the awards given by RHS (Royal Horticultural Society) judges, this year on the theme of “Summer of Love”. (Photo by Toby Melville/Reuters)

In this photo taken on Thursday, March 7, 2019, the sun rises over the star on the spire on top of a Stalin-era skyscraper, now the Radisson Royal Hotel on the banks of the Moskva River in Moscow, Russia. (Photo by Dmitry Serebryakov/AP Photo)