I assume that you know that it is spread in respiratory droplets that envelop the virus particles and those are much larger and greatly reduced from emission into the shared airspace in buildings by a mask. Nothing is 100% but reduction of viral load & distance of viral particles that an infected person emits helps reduce the odds of infecting others and also the level of exposure which research has shown to reduce the severity of infections in those exposed. Masks and even just a single layer of a bandana have been shown to reduce both the quantity of viral… Read more »