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Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low

Wouldn't UV-light in ducting generate ozone? Even relatively small amounts of ozone can be harmful. > When inhaled, ozone can damage the lungs. Relatively low amounts can cause chest pain, coughing, shortness of breath and throat irritation. [0] [0] https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#harmful-ozone https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-...

RetpolineDrama 4y ago
Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.
Eisenstein 4y ago
Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...
- wnevets 4y ago
  >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.
- jefftk 4y ago
  > Standard germicidal UV-C lights are ~250nm. The article is about KrCl 222-nm lights, which people want because they're safe [1] to shine on people, unlike Hg 254-nm lights. [1] Probably -- I'd like to seem some specific additional experiments before widespread deployment.
  - lazide 4y ago
    222nm is not safe to shine on anyone! It will definitely cause skin cancer. 254nm is also not safe. 254nm destroys ozone, interestingly. 240nm and smaller (160nm being the highest producing freq.) produce ozone. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
    - jefftk 4y ago
      I don't see anything in your link about 222nm causing skin cancer? It's short enough that it shouldn't be getting through the outermost layer of skin, which is dead.
      - lazide 4y ago
        Welders have plenty of experience to contradict it. UV-C is usually blocked by the atmosphere, and most people don't get exposed to it directly - so it rarely comes up. But if you're sitting next to a UV-C generator, don't. It cleaves DNA the same as UV-B, and there is no reason to think it isn't cancer causing. There are a number of areas that can get exposed that have very thin epidermis, or none at all (eyes), though eyes would get retinal keratosis not cancer. That said, hopefully no one is spending enough time close to a high enough power UV-C source for this to REALLY be a problem. Welding Cite - [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/] Notably, while having a higher skin cancer risk despite being inside a lot (shop welders, not shipyard welders), the vast majority of welders in that sampled population will have been wearing heavy protective clothing continuously. There was a noticeable increase in risk of skin cancer on the neck, which is one of the few areas that is not always adequately covered. Anecdotally, I knew folks who didn't wear proper full coverage PPE when welding and welded a lot (auto body repair in one case, farm equipment repair in another), and both died in their early 40's from multiple malignant melanomas. One of them, it was 10+ all at once, and he died in less than a year. No one was surprised, unfortunately. They were ALWAYS sunburned from it, and they didn't spend a huge amount of time outside otherwise. That is a pretty broad spectrum source though. UV-C As Potentially Mutagenic/Causing Damage not caught by normal replication suppression mechanisms - [https://pubmed.ncbi.nlm.nih.gov/9951833/ https://pubmed.ncbi.nlm.nih.gov/9951833/] UV-C will also have no problem converting all sorts of organic chemicals into interesting, and often more toxic versions (albeit killing any organisms relying on their original structure in the process), same as UV-B or UV-A.

RetpolineDrama 4y ago

Carrier at least claims their UV upgrade does not produce ozone. Not sure how accurate that is though.

Eisenstein 4y ago

Ozone is produced at 185nm. Standard germicidal UV-C lights are ~250nm. The issue is that some germicidal bulbs do not filter out the lower wavelengths and thus produce ozone (sometimes on purpose since ozone is also germicidal). See [0]. [0] https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation#Lamps https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...

wnevets 4y ago
>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.
jefftk 4y ago
> Standard germicidal UV-C lights are ~250nm. The article is about KrCl 222-nm lights, which people want because they're safe [1] to shine on people, unlike Hg 254-nm lights. [1] Probably -- I'd like to seem some specific additional experiments before widespread deployment.
- lazide 4y ago
  222nm is not safe to shine on anyone! It will definitely cause skin cancer. 254nm is also not safe. 254nm destroys ozone, interestingly. 240nm and smaller (160nm being the highest producing freq.) produce ozone. [https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391 https://onlinelibrary.wiley.com/doi/full/10.1111/php.13391]
  - jefftk 4y ago
    I don't see anything in your link about 222nm causing skin cancer? It's short enough that it shouldn't be getting through the outermost layer of skin, which is dead.
    - lazide 4y ago
      Welders have plenty of experience to contradict it. UV-C is usually blocked by the atmosphere, and most people don't get exposed to it directly - so it rarely comes up. But if you're sitting next to a UV-C generator, don't. It cleaves DNA the same as UV-B, and there is no reason to think it isn't cancer causing. There are a number of areas that can get exposed that have very thin epidermis, or none at all (eyes), though eyes would get retinal keratosis not cancer. That said, hopefully no one is spending enough time close to a high enough power UV-C source for this to REALLY be a problem. Welding Cite - [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5640727/] Notably, while having a higher skin cancer risk despite being inside a lot (shop welders, not shipyard welders), the vast majority of welders in that sampled population will have been wearing heavy protective clothing continuously. There was a noticeable increase in risk of skin cancer on the neck, which is one of the few areas that is not always adequately covered. Anecdotally, I knew folks who didn't wear proper full coverage PPE when welding and welded a lot (auto body repair in one case, farm equipment repair in another), and both died in their early 40's from multiple malignant melanomas. One of them, it was 10+ all at once, and he died in less than a year. No one was surprised, unfortunately. They were ALWAYS sunburned from it, and they didn't spend a huge amount of time outside otherwise. That is a pretty broad spectrum source though. UV-C As Potentially Mutagenic/Causing Damage not caught by normal replication suppression mechanisms - [https://pubmed.ncbi.nlm.nih.gov/9951833/ https://pubmed.ncbi.nlm.nih.gov/9951833/] UV-C will also have no problem converting all sorts of organic chemicals into interesting, and often more toxic versions (albeit killing any organisms relying on their original structure in the process), same as UV-B or UV-A.