I've appreciated your content on far-UVC, and I made this account just to ask this question, because I've been looking all over the internet and haven't found any answers: apart from ozone, how much data is there on photodecomposition? I'm particularly concerned about whether there's the potential for phosgene to be produced if chlorinated solvents are exposed to the lamps.
Here is a setup for producing phosgene at room temperature by exposing oxygen and chloroform to UV light at 184.9 nm and 253.7 nm. I don't know enough about this sort of chemistry to determine whether the absorption bands are sharp enough that 222 nm light would produce substantially less phosgene, or whether the light from the germicidal lamp just isn't intense enough to produce dangerous amounts of phosgene even if someone sprays chlorinated degreaser everywhere.
It may be that someone with a lot more knowledge has already dismissed this as obviously not a problem, and that's why there's no mention of it. However, since I cannot tell the difference between that and a potentially fatal (if unlikely) hazard being overlooked, I thought it best to ask.
Thanks for asking about this! I just did a little research, and while it looks like the frequency range at 222nm would likely be sufficient for this reaction, there are three reasons why it's not a concern in practice:
The UV light is not very strong: levels that would produce appreciable toxic gas would already be unsafe for human eyes and skin
Cleaning products almost always contain stabilizers to absorb free radicals
Human spaces have some ventilation (or we'd get too much CO2!) so any tiny amounts that were produced wouldn't build up
I like my far-UVC Aerolamp a lot, but haven't been using it much: each time I wanted to get it out I needed to put it up on a tall stand, and ensure it wasn't going to get knocked over. This evening I attached it to the wall, which is great:
It's very light and uses a 1/4" photo mount, so I used these simple cheap tiltable ones. The goal is to get it as high as possible for safety, and angled down so you're not wasting half the output on the ceiling. They were $9 for four, so if you are in Boston and want one I have three more. It unscrews easily, so it's not hard to take down when I need it portable again.
Aside: I'm very happy to lend it to people putting on events, as long as you'll be careful with it. For example, it went to YTS this year.
It comes with a very blue cable, and to make it less obtrusive I got a cheap white one to tuck up in the molding:
I don't have a convenient switched outlet, but remote-controlled outlets have gotten so cheap these days that it seemed worth setting one up. I put it pretty high up and labeled it, so guests wouldn't mistake it for a regular light switch.
It keeps my elevated air purifier good company.
Here's what it looks like covering the living and dining room:
I chose to put it on the dining room side because the living room has more existing air cleaning capacity (3x AirFanta 3Pro).
My ceiling is only 8'5", so the highest I can get the lamp is 8'1". If people are standing, per Illuminate it hits ACGIH 8-hr limits after 6.3hr, so I'm planning to run it for at most 5hr/day by default. Because dose falls inversely to with distance squared, however, if people are sitting (ex: eating around the table) then the additional 15" of height reduces the worst-cas edose by a factor of 2.4, which keeps you below safety limits in basically any plausible scenario.
I'm glad to have it set up semi-permanently, and this should save time setting up for EA Dinners and other crowded gatherings!