WHAT IS THE WORLD’S SMELLIEST SUBSTANCE?
Heather Curran
This question isn’t as subjective as it sounds because scientists can quantify the ‘smelliness’ of a chemical by how few molecules are needed for the human nose to detect it. In these terms, a group of sulphur compounds called thiols are way out in front. In fact, tiny amounts of methanethiol are deliberately added to natural gas, which is otherwise odourless, so people can detect gas leaks. But the smelliest thiol of all is thioacetone, which caused widespread fainting and vomiting when a small amount was accidentally released in the German city of Freiburg in 1889.