[HN Gopher] Two-Twenty-Two
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Two-Twenty-Two
Author : _Microft
Score : 69 points
Date : 2022-10-10 18:13 UTC (1 days ago)
(HTM) web link (www.science.org)
(TXT) w3m dump (www.science.org)
| kurthr wrote:
| I love me some Derek Lowe, but this one really beat around the
| bush.
|
| Article is about disinfection with 222nm light, which has some
| very useful and well tested properties.
| at_a_remove wrote:
| As someone with a photosensitivity disorder, anything shorter
| than 405 nm spells trouble for me. This is kind of a nightmare
| scenario really.
| jefftk wrote:
| Are you sure something as low 220nm would? This is short enough
| that the chemical changes it causes are very different than
| longer UV.
| at_a_remove wrote:
| It sure will be exciting to find out.
| tln wrote:
| Sorry to hear that :(
|
| Is there anything you use to detect light like this? Digital
| spectrum meters or UV detector keychain etc.
| at_a_remove wrote:
| Pain, really. Anything shorter than "purple" is enough.
|
| I just can't imagine how I would function if this sort of
| thing became commonplace.
| _0ffh wrote:
| According to the article, 222nm would already be stopped by
| the thin coat of dead cells on the skin. So it shouldn't
| penetrate far enough to cause any trouble.
| mig39 wrote:
| Would organisms eventually evolve to be resistant to 222nm light?
| thaumasiotes wrote:
| Yes, of course.
| chromatin wrote:
| Given that the articled discusses 222 nm light being harmless to
| humans, and acknowledging that 254 nm is known to be dangerous, I
| am concerned that wide/universal deployment of such systems might
| lead to situations where poorly constructed or serviced equipment
| might emit dangerous wavelengths.
| _tom_ wrote:
| This needs more informative title.
| jiggawatts wrote:
| > "...led them to conclude that at the current OSHA regulatory
| standard for continuous 222 nm light exposure that you would see
| 90% viral inactivation at 8 minutes and 99% inactivation in about
| 16 minutes."
|
| Something I learnt about disinfection protocols is that they're
| measured on a logarithmic scale, much like volume (decibels),
| earthquakes, etc...
|
| So when you see marketing saying things like "kills 99.9% of
| germs", think of that as "strength 3" because it has three nines.
|
| The article mentions strengths from 1 to 2, which is about as low
| as it gets and still have "some" effect.
|
| Hospital grade disinfectants are more like 99.99% to 99.999% ("4"
| and "5" strength), for comparison. Autoclaves and the like can go
| to "12"!
|
| This is because bacteria grow exponentially, so to remove "one
| doubling" time, you have to halve the numbers. To remove "two
| doublings", you have to quarter the numbers, and so forth. In
| other words, every unit of safety time you want to buy requires
| an exponential increase in disinfection.
|
| Keep this in mind when shopping for cleaning products! The
| difference between "99%" and "99.9%" is just "one" doubling time,
| not a tenfold improvement.
|
| More reading:
| https://static1.squarespace.com/static/5f42a255876c3361a6189...
| divbzero wrote:
| > _What 's even better than [effective drugs and vaccines] are
| public health measures that are taken even more broadly and don't
| require individual actions. In the industrialized world, we took
| many of these a long time ago, things like providing clean water
| without pathogens floating around in it. It comes as a shock to
| us when that layer of defense breaks down, because we're so used
| to it that we take it as part of the natural order of things._
|
| If disinfection with 222nm light or a similar safety measure
| becomes so commonplace that we take for granted, that would be a
| remarkable shift and a small silver lining to the COVID pandemic.
| anikan_vader wrote:
| The Atlantic article that this one links to admits that negative
| side-effects of UV-C have been known since at least the 40's:
|
| >> But though Wells and other early pioneers of this technology
| could shine their 254 nm lamps aloft to clean the air floating in
| the upper portion of rooms, or use the light inside vents or
| ducts, they couldn't actually shine them downward, directly onto
| the occupants of rooms, without ill effect. That's because,
| although 254 nm inactivates pathogens, it also causes skin and
| eye damage at certain doses.
|
| This is a very contradictory tone with the article, which
| essentially claims UV-C is totally safe for humans. EDIT: The
| author of the article explicitly acknowledges this.
| high_pathetic wrote:
| Additionally, the UV radiation produces ozone, which is harmful
| to breathe.
| BoppreH wrote:
| Dr Lowe explicitly mentions the danger of 254 nm:
|
| > That's very much as opposed to (say) 254 nm light, which
| starts doing damage immediately due to greater penetration into
| animal tissue.
|
| and that 200-222 is safer because of lower penetration.
|
| > down in that range, the penetration of such light is only a
| few microns, and it doesn't even get past the dead cells on the
| surface of the skin and the cornea of the eye!
| anikan_vader wrote:
| My bad, thanks for the correction. I am surprised though - I
| thought higher frequency waves were more dangerous, but
| clearly that is not universally so.
| tingletech wrote:
| the article (titled Two-Twenty-Two presumably because it is
| about this specific wavelength vs the whole UV-C range) does
| say "222 nm light does not induce DNA damage in mice, even at
| much higher flux than would be used for disinfection. That's
| very much as opposed to (say) 254 nm light, which starts doing
| damage immediately due to greater penetration into animal
| tissue."
| 1970-01-01 wrote:
| Seems like we should add ~222 UV light to many more home
| appliances. Home water tanks with lower temperatures, dishwashers
| with water-free sanitization cycles, refrigerators could include
| a self-cleaning option, etc. If it holds bacteria and shouldn't,
| use UV to sanitize.
| zasdffaa wrote:
| How about we stop worrying so much about germs unless killing
| them wholesale is shown to produce a _significant_ increase in
| health. I am pretty sure bactericides etc. are being pushed by
| industry for their profit not our wellbeing at all.
| tourist2d wrote:
| I don't know why you want a significant increase in health.
| I'd switch over even if it were a mild increase.
| 1970-01-01 wrote:
| Killing germs is part of modern daily life. You shower, do
| dishes, brush your teeth, and wash clothes. It's much, much
| cheaper to shine a UV light onto a surface for a few minutes
| compared to using soap and other chemicals. UV toothbrushes
| and toothbrush cleaners are already sold online.
| zasdffaa wrote:
| Me: let's not do <thing> unless we have a reason.
|
| You: We should continue doing <thing> because we already do
| <thing>
|
| "carry on" is not a reason to do anything. I literally
| can't understand how you are thinking to post such a non-
| justification.
| 1970-01-01 wrote:
| Sorry, I don't understand where you are going with this
| comment. I was explaining how UV can be used to save
| energy. You're arguing against that?
| funnymony wrote:
| GP argues against killing microbes. (With some nuance)
| zasdffaa wrote:
| If you're talking cost then maybe. In the right places
| such as hospitals, very likely. I'm questioning that we
| should do that indiscriminately in other places such as
| in homes. We have highly developed immune systems, let's
| not risk weakening them. And not doing it costs nothing
| at all.
| bobsmooth wrote:
| Germs cause disease. I know germ theory is pretty new but
| its established science.
| zamalek wrote:
| Germs _also_ cause immunity. You do need exposure
| (vaccines help, but aren 't enough).
| shard wrote:
| Agreed. More sterilization also goes against what we should
| do per the hygiene hypothesis
| (https://en.wikipedia.org/wiki/Hygiene_hypothesis, which
| states that early childhood exposure to germs is necessary
| for the development of a healthy immune system), especially
| around children in non-hospitalization situations.
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