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> recently published studies have demonstrated that UV light at 222nm has the same germicidal capabilities of 254nm light without damaging skin or eyes. 222nm

> recently published studies have demonstrated that UV light at 222nm has the same germicidal capabilities of 254nm light without damaging skin or eyes. 222nm may have the same capabilities, but not the same efficacy and efficiency as 254nm (or 185nm, the germicidal action if which is it creates ozone, which does the disinefecting). Still, if it works but just takes longer without the sunburn and blindness, whether by proximity to 254nm such that some 254nm is still present, and/or by proximity to 185nm such that ozone is still created, well, ok.

hedgehog 4y ago
According to the linked article: "While the effects on live tissue are diminished, Far-UV (222 nm light being the most prevalent) has increased efficacy for killing bacteria and viruses."
- Maursault 4y ago
  That's misleading, increased efficacy as opposed to what? A control? It's not more than 254nm, which has been long proven, in repeated studies, to be the most efficient germicidal wavelength, decreasing in near wavelengths depending on how close they are to 254nm. 222nm is only 32nm of wavelength difference to 254nm, and I'll wager that even 238nm is more efficient than 222nm, but maybe 238nm burns skin. 222nm is nearly half way between 185nm and 254nm, so it will have some of the germicidal effects of both wavelengths, but it won't be more than either 185nm or 254nm. But it may be enough, and if it doesn't hurt people, then kudoes.
  - scythe 4y ago
    >254 nm ... which just happens to be exactly the second spectral line of a low-pressure mercury-vapor lamp. Actually 253.7. The other line is 184.5. Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Efficient far-UV sources tend to be few and far between. It would be an awfully big coincidence if the two major spectral lines of an Hg plasma just happen to be the two ideal wavelengths for disinfection. FWIW, zinc vapor has a persistent line at 214 nm, but I've never heard of this being applied in a commercial bulb. Other relevant possibilities are all toxic.
    - Maursault 4y ago
      > Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Studies, and yes. Mercury vapor's spectral emission is just a happy coincidence and why mercury vapor lamps are used for germicidal applications. The germicidal LED's they make are 255nm. But 254nm, not 255nm, not 253.7nm, is the most efficient wavelength for germicidal applications, in that it kills the most bugs the fastest. Please don't make me dig up the studies, please find them yourself, there are plenty, and it'll mean more to you.
  - viraptor 4y ago
    Just read the article. It's "compared with 254 nm light". Both sentences are in the abstract.

hedgehog 4y ago

According to the linked article: "While the effects on live tissue are diminished, Far-UV (222 nm light being the most prevalent) has increased efficacy for killing bacteria and viruses."

Maursault 4y ago
That's misleading, increased efficacy as opposed to what? A control? It's not more than 254nm, which has been long proven, in repeated studies, to be the most efficient germicidal wavelength, decreasing in near wavelengths depending on how close they are to 254nm. 222nm is only 32nm of wavelength difference to 254nm, and I'll wager that even 238nm is more efficient than 222nm, but maybe 238nm burns skin. 222nm is nearly half way between 185nm and 254nm, so it will have some of the germicidal effects of both wavelengths, but it won't be more than either 185nm or 254nm. But it may be enough, and if it doesn't hurt people, then kudoes.
- scythe 4y ago
  >254 nm ... which just happens to be exactly the second spectral line of a low-pressure mercury-vapor lamp. Actually 253.7. The other line is 184.5. Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Efficient far-UV sources tend to be few and far between. It would be an awfully big coincidence if the two major spectral lines of an Hg plasma just happen to be the two ideal wavelengths for disinfection. FWIW, zinc vapor has a persistent line at 214 nm, but I've never heard of this being applied in a commercial bulb. Other relevant possibilities are all toxic.
  - Maursault 4y ago
    > Are you sure that the study you read isn't just reporting this wavelength as ideal because we have a convenient source of it? Studies, and yes. Mercury vapor's spectral emission is just a happy coincidence and why mercury vapor lamps are used for germicidal applications. The germicidal LED's they make are 255nm. But 254nm, not 255nm, not 253.7nm, is the most efficient wavelength for germicidal applications, in that it kills the most bugs the fastest. Please don't make me dig up the studies, please find them yourself, there are plenty, and it'll mean more to you.
- viraptor 4y ago
  Just read the article. It's "compared with 254 nm light". Both sentences are in the abstract.