I'm not familiar with your background but your post is one of the most inclusive among many professional ones. Being an expert of CIE in this field and having numerous patents on optics let me humbly add a number of short comments.
Harmful effect of UVC is a common place, but it is greatly exaggerated as a result of misinterpreted raw data which generally assume much larger irradiated areas of our body. And in any case they look as laughing stock compared to other radiation treatments.
UVC is the only method to kill 99.9% of any Virus, given a sufficiently long irradiation time.
Quoted by you figure of merit is more typical for FOMITES (surfaces) rather then droplets.
Just imagine that we have a compact wearable Headmouted system concentrating all emitted light only on areas of your mouth-nose of say 10cm^2 and is absorbed there. Thus principally it is possible to completely "sterilize both you and a user (two-way action) with say 100 mW lamp with less than 0.1s of through-flow time.
I'm close to form a consortium and start production shortly.
Roko, kudos.
I'm not familiar with your background but your post is one of the most inclusive among many professional ones. Being an expert of CIE in this field and having numerous patents on optics let me humbly add a number of short comments.