4 ms·

>Ozone is produced at 185nm Where did you find that 185nm number? Everything I see on google says ~250nm, not to mention the original post is about 222nm UV.

lazide 4y ago
~ 250nm actually destroys ozone. Smaller than 240nm creates it, to various degrees, with the ideal frequency being 160nm. 185nm is 'produces a noticeable amount'. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
- wnevets 4y ago
  So the 254nm referenced by the linked product could actually reduce the amount ozone in the air? Assuming of course it wasn't also emitting lower frequencies.
  - lazide 4y ago
    Yes, but.... if you look at the paper, most of these lamps have some degree of lower wavelength light production. Some of them mitigate it through the glass they use, some of them make it worse. There is no good or easy way to tell. :(
  - jefftk 4y ago
    The linked product peaks at 222nm and is filtered to exclude longer wavelengths. It's being compared to Mercury vapor lamps that peak at 254nm.
    - wnevets 4y ago
      The blue tube product linked in the original comment I replied to says 254nm. https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/
      - jefftk 4y ago
        Whoops, sorry! I was trying to talk about the linked article, and missed that the comment had brought in a different product.
  - etiam 4y ago
    I'm certainly not a physical chemist, but at that sort of energy levels wouldn't it rather be liable to drive the gas mix towards some sort of equilibrium? I'd imagine it breaks down molecular oxygen (some of which goes on to form ozone), and it breaks down ozone (some of which goes on to re-form ozone). At any rate, that seems like altogether too radical to be desirable near living creatures whose well-being one cares for.
    - lazide 4y ago
      Yup, and the paper I linked has some detailed analysis of some scenarios. In some cases (particularly bad mercury vapor lamps), it can produce dangerously high ozone levels (50x EPA safe working limits). In others, no foreseeable issues even if run 24x7. So, uh, maybe don’t buy cheapo units off Amazon unless you have some way to see/test what they’re doing.

lazide 4y ago

~ 250nm actually destroys ozone. Smaller than 240nm creates it, to various degrees, with the ideal frequency being 160nm. 185nm is 'produces a noticeable amount'. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]

wnevets 4y ago
So the 254nm referenced by the linked product could actually reduce the amount ozone in the air? Assuming of course it wasn't also emitting lower frequencies.
- lazide 4y ago
  Yes, but.... if you look at the paper, most of these lamps have some degree of lower wavelength light production. Some of them mitigate it through the glass they use, some of them make it worse. There is no good or easy way to tell. :(
- jefftk 4y ago
  The linked product peaks at 222nm and is filtered to exclude longer wavelengths. It's being compared to Mercury vapor lamps that peak at 254nm.
  - wnevets 4y ago
    The blue tube product linked in the original comment I replied to says 254nm. https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/ https://www.amazon.com/Blue-Tube-UV-Light/dp/B00D48XDO0/
    - jefftk 4y ago
      Whoops, sorry! I was trying to talk about the linked article, and missed that the comment had brought in a different product.
- etiam 4y ago
  I'm certainly not a physical chemist, but at that sort of energy levels wouldn't it rather be liable to drive the gas mix towards some sort of equilibrium? I'd imagine it breaks down molecular oxygen (some of which goes on to form ozone), and it breaks down ozone (some of which goes on to re-form ozone). At any rate, that seems like altogether too radical to be desirable near living creatures whose well-being one cares for.
  - lazide 4y ago
    Yup, and the paper I linked has some detailed analysis of some scenarios. In some cases (particularly bad mercury vapor lamps), it can produce dangerously high ozone levels (50x EPA safe working limits). In others, no foreseeable issues even if run 24x7. So, uh, maybe don’t buy cheapo units off Amazon unless you have some way to see/test what they’re doing.