Bioloon CEO Charlotte Melia holds a sample of biodegradable rubber at a laboratory at Imperial College in London, on August 19, 2026. A symbol of celebration but an ecological nightmare, the party balloon is undergoing a green revolution: researchers in London claim to have developed the first fully biodegradable model, which they plan to bring to market within two years. (Photo by HENRY NICHOLLS / AFP via Getty Images) / TO GO WITH STORY by Alexandra DEL PERAL