[bsder]

> The claim that 222nm is an effective disinfectant seems to directly contradict the claim that it cannot penetrate skin. In particular, if it bounces off dead skin cells, and the environment contains dust, how can it possibly kill things on the dark side of the dust particles?

It penetrates single cell walls but nothing deeper.

People are mostly interested in 222nm for doing things like sterilizing air circulation and handheld wands. You can put a very high flux without worrying about accidentally exposing someone to a hazardous level of UV light.

People aren't trying to sterilize skin directly (as far as I know), but, even there, it might help healthcare workers. Washing your hands or coating it with alcohol is nasty over time. Being able to hold your hands in a device for 15 seconds and sterilize it rather than having to dump alcohol on them could be an improvement.

[hedora]

"Airborne" viruses are almost always traveling in protective droplets of fluids, sloughed cells, etc, etc. Direct contact with air kills them. So, how does the UV get inside the droplet so that it can reach the pathogen?