Are there any particular wavelengths of UV that are particularly effective, or which are not effective at all against the virus?
https://smile.amazon.com/gp/product/B07KYVRVX7/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I bought some of these UV lights a month ago. They are no longer in stock. I forget the wavelengths. Some have just the UV light, and most in the market have combined UV and ozone.
Note - the light is very damaging to eyes, skin and other living organisms (plants, animals, etc.) I see that people are developing lights in another frequency that are not harmful to humans, but will still destroy the virus. But iirc those products are another 1 to 2 years out.
Ozone is also very bad for humans, pets and plants. But as a gas it can “reach” into all the corners of the room, fabrics, etc.
Both types are useful to have.
UVC is what you want. It is not natural so nothing has any defense against it.
I deal with industrial UVC used for UV inks. We have some irradiators that pump out around 600 Watts. They are NASTY. If you expose one in a warehouse outside of the safety enclosure, it looks like someone opened the Arc of the Covenant in Raiders of the Lost Ark. It also creates an insane amount of Ozone.
The problem with these lights is they are very damaging to the human eye. You need to have safety goggles designed for these wavelengths. If you can look at it without goggles, it's not strong enough to be a germicide.
UVA and UVB also disinfect, but are not nearly as effective.
Scientists found 222 nanometer far-UVC light was just as effective as broad spectrum UV light at killing and deactivating the aerosolized influenza virus. (and is safer)