Far-UVC is something people have talked about for years in a "that would be great, if you could buy it" sort of way. Coming soon, once someone actually makes a good product. But the future is now, and it costs $500.
Many diseases spread through the air, which is inconvenient for us as creatures that breathe air. You can go outside, where the air is too dilute to spread things well, but it's cold out there, and sometimes wet. You can run an air purifier, but cleaning lots of air without lots of noise is still the world of DIY projects. Ideally you could just shine some light, perhaps in the 222-nm range, which would leave people alone but kill the viruses [1] and bacteria. Yes, let's do that!
Last year if you asked "if far-UV is so great, why isn't it everywhere?" one of your answers would be:
There are very few providers, and hardly any of them sell an off-the-shelf product. You usually can't just buy a lamp to try it out—you have to call the company, get a consultation, and often have someone from the company come install the lamp. It's a lot of overhead for an expensive product that most people have never heard of.
This has changed! You can buy an Aerolamp for $500, shipped. Proudly displayed at Thanksgiving:
Here are four silently cleaning a whole lot of air at a dance I help organize:
At $500 this is out of (my) Christmas gift range, but I think we're now at the point where dances, churches, offices, rationalist group houses, schools, etc. should consider them.
(I have no stake in Aerolamp and they're not paying me, I'm just very excited about their product.)
[1] Ok, yes, I know viruses "can't be killed" because they're "not
alive", but far-UVC causes them to become unable to infect and
replicate which is close enough to "killed" for me.

EDIT: Basically answered here... https://aerolamp.net/pages/faq
Lazy question What big an area can one $500 UVC cover? Do those 4 in the dance room genuinely clean the whole area?
Surely to be actually mass-practical we need one that can just be a lightbulb and attach to a regular fitting? Obviously it must be harder than all that,,,,
How big an area they cover depends on how long the sight lines are: the more air the light can travel through the more it can clean. It's not linear, though, and there are different effects for different pathogens because some are quickly inactivated with low levels of UVC and others need more. The modeling tool Illuminate can be very useful here; here's something I wrote up when I was figuring out what made sense for the dance hall: Assessing Far UVC Positioning.
Wow awesome thanks for letting me know!