The start-up UM Systems from the US state of Colorado, for example, has developed mouth and nose protection that is technically more similar to a modern air purifier than a mask. When the wearer inhales, a classic replaceable filter cloth first fishes 95 percent of all microparticles and pathogens out of the air. That already corresponds to an FFP2 mask. The air is then passed through a coil with UV light that sterilizes the air. The UVMaskAs the device is called, it can purify ten times more air than the person wearing it normally inhales. This ensures a low breathing resistance. In the end, 99.99 percent of the pathogens are filtered or rendered harmless. The UV light changes the genetic material of the viruses in such a way that they can no longer multiply, even if a person inhales them. And the device not only protects the wearer of the mask. The exhaled air is also sterilized.