There are also alternate forms of Upper-Room GUV that can work with lower ceilings. Namely, Egg-Crate GUV- which is even more powerful than conventional louvered Upper-Room GUV while being safer at the same cost, and Crown-Molding LED GUV, which is completely invisible and dimmable to TLV. Rooms with either of these could hit 20 eACH easily at negligible cost per year and leave filters to mop up PM2.5 and any secondaries.

ELI5: A lot of what I argue about/for with clean air boils down to cleaning with one of those Swiffer things, or a mop and bucket. Swiffers are cheaper to buy than a good mop and bucket, arguably easier to use, and work very well- but the long-term cost of ownership, particularly if you make them a standard and implement them at scale, is tremendous. A good mop and bucket is a higher upfront expense, harder to use, but is also far more powerful and has a far lower cost of ownership. This is very, very loosely the situation- filtration=Swiffer, mop=GUV, but keep in mind you really need *some* filtration because it's the only way to deal with pollution. No filtration is not an option- but all filtration seems sub-optimal also. Filters require ongoing consumables- which will mean constant budget struggles because people seem ideologically opposed to the idea of clean air, GUV needs about $5-10 in maintenance a year. Power consumption is similar. If you ignore actual feasibility and pesky things like money, and environmental impact, just recommending a Swiffer everywhere is the obvious safe choice. It also completely ignores the real world- where money and environmental impact actually do exist and Swiffer alone is a horrifically wasteful solution to cleaning floors compared to both Swiffer and mop.