Is there a quantification of the effect of this on skin microbiome as of now? I would not like to kill all of the bacteria on my skin.
viruses are much more vulnerable than skin bacteria, although that doesn't rule out microbiome damage entirely.
This is great!
What do you think of UVC lamps that you just kind of stick into a hole in your HVAC intake ducts? Some of them are really cheap, most seem to be 254nm, no idea if any are any good. Would be really convenient if it works well.
Putting lamps in ducts is not very different from putting filters in ducts; but with the downside that I'm a lot more worried about fraudulent lamps than filters. I guess it's easy to retrofit a lamp into a duct, whereas a filter slows the air; but you probably already have a system designed with a filter.
The point of lamps is to use them in an open room where they cover the whole volume continuously.
https://www.nature.com/articles/s41598-025-09241-2
Corneal safety assessment of germicidal far UV-C radiation
Abstract
Far UV-C radiation (200–240 nm) is a promising alternative to conventional UV-C for disinfection in occupied spaces, offering strong germicidal efficacy with reduced skin risk. However, its ocular safety remains unclear, as most studies relied only on non-human corneal models with physiological differences. This study investigated UV-induced DNA damage in the epithelium, stroma, and endothelium of ex vivo human corneas and porcine corneas, and reconstructed human cornea epithelium (RHCE) using immunohistochemistry. Samples were exposed to 222 nm, 233 nm, 254 nm, and broadband UV-B (280–400 nm) radiation in the presence of real human tears. Compared to human corneas (26 μm mean epithelium thickness), porcine corneas (110 μm) and RHCE (79 μm), showed reduced UV penetration. In human corneas with a thin epithelium, far UV-C exposure led to epithelial and anterior stromal damage, underscoring the epithelium’s protective function. Optical properties using porcine corneas confirmed the immunohistological findings, validating wavelength-dependent penetration depths. Simulations suggest that in intact human corneas, damage-relevant intensity of 222 nm light reaches the middle of the epithelium, while for 233 nm, it reaches the basal layer. These findings support the relative safety of far UV-C, especially 222 nm, for intact corneas. However, potential DNA damage accumulation after repeated exposures underscores the need for further research on long-term ocular effects.
I hadn't seen that study, thanks for sharing! I've added it to faruvc.org, and added a warning that people shouldn't consider 233nm LED sources as equivalent to 222nm KrCl sources.
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.