but viruses and bacteria are probably never traveling alone. imagine someone sneezing on table. they will be embeded in pieces of dead skin or tiny droplets of phlegm, saliva, etc... in the linked article they are using it to disinfect surfaces in passenger aircraft. unless it can penetrate a bit, i don't see how it can be effective.
also viruses (eg. HIV, Coronavirii,...) are often killed by oxygen in air, dry out or die in other ways when not floating in bodily fluids.
The light doesn't need to kill 100% of pathogens to be effective at decreasing risk. I agree that if the pathogen is on a table but under a protective layer the levels of UVC we're talking about aren't going to do anything to it. But the main concern is with airborne viruses which mostly aren't very protected.
also viruses (eg. HIV, Coronavirii,...) are often killed by oxygen in air, dry out or die in other ways when not floating in bodily fluids.