UVC, the kind that kills pathogens harms the skin and eyes and creates ozone. The article talks about using “Upper Room UV” which is just lights posted a safe distance away from humans above them which makes it considerably less effective at killing pathogens at the human level and also now theres a whole area of space where you cant go without risking harm from UVC like being on a ladder or some other platform.
Yeah UV light alone is safe, but by the end of the article it mentioned that far-UV light also triggers a chemical reaction that creates ozone, which is dangerous. It needs a good ventilator system to make it safer.
UV-A is quite safe, UV-B are the harmful wavelengths that cause the harmful effects of sunlight, UV-C is much worse.
The light that kills viruses, UV-C quickly damages your eyes quite severely, and also burns your skin and can cause skin cancer far, far faster than UV-B.
I've been using both a dedicated Ozone generator in unoccupied rooms and a UV sanitizing light built into the HVAC system. Seems to be improving allergies.