Upper-room UV in smoke alarms - mains wired ones obviously

Like this one: 

Pic from https://en.wikipedia.org/wiki/Smoke_detector

Sora gives it a go:

It'd come out close to 360 degrees at ceiling level. The smoke alarm would still be a smoke alarm and still have the 9-volt battery backup. This isn't for the 9-volt battery types, it's for the mains wired ones. In the UK that's now the rule rather than the exception. They could be homeowner replacements for the existing ones, and maybe have the same ten-year life.

SARS-2, SARS-1, flu, TB, Polio, Smallpox, RSV would all be zappable if the air currents in a room wafted up to the ceiling as they are all airborne-too  Norovirus has a ariborne transmission mechanism too, in addition to other mechanisms.  This wouldn't do much for e-coli, salmonella, and a great many other older-than-2020 diseases.

How to time their planned on/off cycles though .. Integrated ESP32?  Or PIR room occupancy with a time delay on the "off". To save electricity you'd make it power off 5 mins after people left a room, but if your sitting room occupants are particularly slow moving, maybe 30 mins.