Each year, hundreds of thousands of people become infected with dangerous germs while they are in hospital – one reason meticulous hand hygiene is a top priority for medical personnel. But it is almost impossible to check whether every centimetre of skin has been sufficiently disinfected. Now, the start-up Heyfair makes hygiene visible: its new disinfectant stains the skin, and disappears completely shortly afterwards. The colouring clearly shows which areas are disinfected – and which aren’t. The colour intensity indicates the degree of the germicidal effect, so everyone can immediately check whether their hands are thoroughly disinfected. A project that will help to prevent infections in future.