
Study shows proof that a safer UV light effectively kills virus causing Covid-19 - signa11
https://www.hiroshima-u.ac.jp/en/news/60119
======
brightball
At my wife’s office, one of the first things we did to prepare to reopen was
install AirOasis units on each AC unit. It’s a UV light inside the return that
is designed to kill anything in the air. The bulbs need to be changed every 2
years.

It won’t do any good in close contact, but at least as air is recirculated we
can be confident that the air is being cleaned effectively.

Had them installed on my house years ago because of an air quality problem and
they worked great.

~~~
nostromo
Installing a HEPA filter is better because it removes pollutants, like smoke,
along with viruses and bacteria.

A side effect people should be aware of is that living in a sterile
environment can harm your children's immune systems, if you have children.

~~~
clairity
absolutely, hepa air filtration is great for all those other reasons,
especially in polluted areas like beijing or (to a lesser extent) LA, but it,
like uv lights, is going to be marginal at best against covid. despite the
media aggrandizement, aerosolization is not a risk factor in most of our lives
outside of relatively unique environments like hospitals.

we keep looking for silver bullets to covid when the most effective solution
is simply distancing. even masks are of limited utility next to distancing
(for a variety of reasons that highly limited and controlled studies don't
negate).

also, we have a huge, free, high-powered wide-spectrum uv emitter bathing us
in light and warmth every day (understanding that some of that specrum gets
filtered out by our atmosphere). hang stuff outside if desired, but it's
really not generally going to make a material difference for covid.

~~~
Scoundreller
> we have a huge, free, high-powered wide-spectrum uv emitter bathing us in
> light and warmth every day.

Iunno where you live, but my jurisdiction actively discourages drinking
beers/wine outside and really wants you to drink on a patio next to a wall or
entirely indoors. I can’t understand why.

[https://nowtoronto.com/food-and-drink/drinks/public-
drinking...](https://nowtoronto.com/food-and-drink/drinks/public-drinking-
toronto-covid-19)

Debatable controls for “order” win out over public health. We’re screwed.

~~~
clairity
yes, being outside is probably the most effective covid mitigation, both for
disabling the virus particles more swiftly and diluting concentrations more
rapidly.

you see this kind of thing a lot in (poorly constructed) regulations, where
the intended effect is intentionally indirect, with lots of negative side
effects that are simply unaccounted for (charitably speaking). it seems like
that rule is primarily intended to prevent disorderly drunkenness and
littering, but instead of addressing that directly, they made a rule saying
don't drink outside anywhere, without regard to potentially negative
consequences.

just brainstorming, targeting disorderly drunkenness with a night in jail
would likely curtail that behavior quickly, if it was truly a problem in the
first place. and just publicly shaming litterers by posting videos online
would probably help curtail littering, along with more, and more visible,
public trash cans.

------
scotty79
I hope this will get popular during this pandemic so all public places will
have some 222nm lights and we'll be able to enjoy way less cases of flu and
colds in the future.

~~~
supernova87a
It kind of has to be done when people aren't there, or within the ventilation
system. You can't have UV lights directly exposing people...

~~~
scotty79
With 222nm you can. I think that's a game changer. Because current UV is
unsafe and restricted to professional applications where risk of misuse is
acceptably low. And 222nm could be applied in commercial and consumer setting
because it's safe for humans.

~~~
ShinTakuya
It's safe for the skin, but I'd question deploying something like that widely
until the other potential side effects are explored. For instance what if
constantly disrupting the surface bacteria on skin had negative long term
effects, even if the skin itself isn't damaged by the light? You can argue
that some level of exposure to viruses is good for your immune system. It's
not proven, but there are certainly some scientists suggesting that excessive
hygiene could be linked to autoimmune diseases, too.

~~~
scotty79
I don't think exposing skin bacteria would be the problem. We are walking
around with plenty of skin covered to keep the reservoir of our microbiome.
Also sunlight is pretty strong disinfectant too ans everybody used to bath in
sunlight for centuries.

And as for hygienic hypothesis ... benefits from hygiene are huge and easy to
observe while link to autoimmune diseases is disputed. And if it exists is
probably through parasites we got rid of, not bateria or viruses that were not
so easy to get rid of.

------
phreenet
I'm no expert on this and this isn't a political post although it's been
politicized, please don't beat me up.

Can someone who is knowledgeable explain to me how this virus could have
evolved in nature with such sensitivity to UV light? I've heard it explained
that the driving belief that this virus was modified in a lab for study of
SARS class viruses and escaped (not released, not as a weapon) is because it
never had to adapt to sunlight. Is there a way that science could answer or
prove this virus is in fact a natural mutation/evolution?

~~~
giarc
Almost all microorganisms as suspectible to UV light. The damage happens at
the DNA level (UV light causes a thymine dimer when two thymine nuclobases are
found together in DNA... thymine being the T in the AGCT of DNA code). This
dimer can result in frameshift mutations which can result in a bunch of
different damage depending on where the TT bases are (some mutations result in
no change, some result in cells inability to replicate etc).

So that's the background on how the UV light acts and disrupts a cells ability
to survive. Now, about your question on how could a virus evolve if UV light
kills it. Easy... the virus doesn't spend a ton of time outside of your body.
Most transmission is person-to-person, there isn't a ton of person-to-surface-
to-person spread therefore it's not like the virus is sitting on a handrail in
the sun for days. Also, as I mentioned above, some mutations don't result in
any change. There is a lot of redundancy in the DNA code (see DNA codon table
1). Not every combination produces a unique aminoacid.

1 -
[https://en.wikipedia.org/wiki/DNA_codon_table](https://en.wikipedia.org/wiki/DNA_codon_table)

My microbiology background is a bit dated, so my facts might be a bit off here
and there.

~~~
brlewis
> Most transmission is person-to-person, there isn't a ton of person-to-
> surface-to-person spread

So I've heard. Doesn't this mean that the UV news is of little impact?

~~~
giarc
Yes, somewhat. I was involved in a project a few years ago where we installed
specialized light housing in the ceiling at the hospital I worked at. These
units had a UV system above it. Basically it would circulate air over UV
lights and therefore would help to decrease the amount of virus floating in a
room. So potentially this could help with a system like that but that only
solves a small portion of person-to-person transmission. Much of it still
happens with-in family groups where you are sitting and
talking/hugging/kissing etc. That's why mask wearing and physical distancing
are key.

------
onetimeusename
>Tests were conducted using Ushio’s Care222 krypton-chloride excimer lamp

This sounds like it is a limiting factor to use. Excimer lamps in general come
with a host of environmental and production concerns. I can't even say
anything about the availability or characteristics of krypton-chloride gas.

~~~
Recursing
Why can't we make the same light using LEDs?

~~~
mooman219
> The band gap of the semiconductor determines the wavelength of the light
> created. The thing about LEDs is that their wavelength is fixed by the
> material. If you want a different wavelength, you generally need a different
> material. Designing materials is hard, which is why the blue led got the
> nobel prize a few years ago.

> The type of material for UV LED is AlGaN, which will have a layer of
> aluminum grown on top of GaN on either Sapphire or SiC substrate. Aluminum
> as metal is conductive, but on AlGaN it is not. To get to a far UV band like
> 222nm, high density of aluminum needs to grow, which becomes non-conductive.
> You would need to compensate it with extremely high voltage current to
> generate really low level of wattage, let alone all the heat it generates.
> So there is no commercial vitality to it. That's the reason the whole
> industry on 222nm is on excimer light.

This is a gist of some comments on:
[https://www.reddit.com/r/Optics/comments/fyqhht/how_are_leds...](https://www.reddit.com/r/Optics/comments/fyqhht/how_are_leds_of_specific_wavelengths_designed_how/)

~~~
reificator
> _I didn 't use the quote feature because it makes reading on phones hard._

Quotes here generally look like the above, the indentation thing is meant for
code and abused to show quotes.

~~~
mooman219
Thanks for the clarification, I misattributed users misusing quotes in code
blocks as the method to quote a text (which causes some pain on small
displays). I've edited the original comment to reflect this.

~~~
reificator
Glad to help!

------
latortuga
Related question: is UV light useful or practical for household sanitizing?
Specifically I'm thinking about dirty dishes in the kitchen. Say, a cutting
board that had raw chicken on it. Would UV light render such a surface safe?
What about in, say, a dishwasher? Could sanitize cycles use less energy that
way?

~~~
ClumsyPilot
UV light can't get into cracks, penetrate dirt, nooks and crannies, so steam
in the dishwasher will do a better job.

It can create Ozone, which kills bacteria and damages respiratory tracks. It
can be a bug or a feature in the right hands.

Hard UV also leaves a nasty sunburn.

In Russia it's used for domesric disinfection for a long time - you turn on a
big lanp and leave the room for a few hours.

~~~
legerdemain
Oh god, homemade "ozonators" like this bare mercury lamp one.[1]

HN sometimes has a misplaced admiration of ex-USSR-ian resourcefulness, but
the cultural climate of top-secret alternative cures and conspirology is
exactly what popularizes breathing cures, DIY bleach injection, "bringing the
light inside," and other desperate, dangerous self-experimentation.

A top result for "ozonator" in Russian advertises that ozone therapy is "used
for wound-healing, immune system recovery, removal of cellulite, and obesity."
Just breathe it in!

[1]
[https://upload.wikimedia.org/wikipedia/ru/0/00/Ozonator.jpg](https://upload.wikimedia.org/wikipedia/ru/0/00/Ozonator.jpg)

~~~
ClumsyPilot
Dude, wth. I am talking about actual proper device that you place in a room,
leave the room and it runs on a timer. That's what normal people have.

Sure there is a fascination with alternative medicine in Russia, but thats a
separate problem, among many others.

~~~
legerdemain
I don't know what kind of modern luxury you live in, but the hobo arc lamp
version is what my family and friends of the family had, and it's the primary
illustration on Russian Wikipedia.

~~~
ClumsyPilot
I mean it's still a mercury lamp, the same thing, just in a metal box and with
a timer. I remember seeing it since age of 12, and noone was trying to make me
breathe ozone.

There were folks advising my parents to treat skin burns with urine of a young
piglet, but fortunately no-one was taking them seriously.

------
jjtheblunt
Is there any virus not imperiled by UV light?

~~~
scotty79
[https://pl.wikipedia.org/wiki/Deinococcus_radiodurans](https://pl.wikipedia.org/wiki/Deinococcus_radiodurans)
should be fairly resistant.

~~~
lgats
en:
[https://en.wikipedia.org/wiki/Deinococcus_radiodurans](https://en.wikipedia.org/wiki/Deinococcus_radiodurans)

------
SashaRuvin
I'm hearing about consumer grade UVC sanitizing devices[1] more, and also see
"electrostatic cleaning"[2] touted by building management companies. I've had
trouble determining if these are just buzzwords or if these really make a
difference.

[1] [https://www.indiegogo.com/projects/uvlyzer-sleek-uvc-
sanitiz...](https://www.indiegogo.com/projects/uvlyzer-sleek-uvc-sanitizing-
phone-accessory#/)

[2]
[https://www.cloroxpro.com/products/clorox/total-360/](https://www.cloroxpro.com/products/clorox/total-360/)

------
blakesterz
This is pretty interesting. It made me think that maybe in the end we'll see
that the way the pandemic was finally brought under control was through a
bunch of things, not just a single thing? It seems like many people are
thinking something like "once we get a vaccine it'll be over", which might be
true. But maybe it'll be a vaccine, and masks, and something like this, and
advances in air filters and a dozen other things that just finally stamp it
out, or reduce it to a level where we don't need to think/worry about it. And
maybe at the same time that'll help greatly reduce the common cold, the flu,
and maybe other things?

~~~
imeron
I think if we reduce the common things (like the cold and flu) too much we
will have more serious infections sweeping across the planet. The immune
system needs training too.

Just like for kids living in a clean environment (no dogs, dirt, etc.) are
more prone to illnesses.

~~~
bryanlarsen
The hygiene hypothesis makes sense to me for allergies, but not for
viral/bacterial illnesses. I'm sure that modern humans are exposed to a _lot_
more colds and flus than prehistoric humans were. Colds and flus spread and
mutate a lot more easily when we have a population in the billions along with
rapid transport.

~~~
LockAndLol
You might be forgetting just what kind of things they were up to at that time.
People got in contact with __a lot__ more dirt that we did. There was much
more manual labor and much less cushy jobs like we have.

The levels of hygiene were nowhere close to the ones we have today. Simple
things like bathing weren't by any means standard depending on which time in
history and part of the world you're talking about.

~~~
bryanlarsen
Dirt doesn't generally contain human cold & flu viruses & bacteria.

~~~
LockAndLol
Dirt doesn't contain bacteria and viruses? Really? So hospitals will rub their
hands in dirt before a surgery, dab your arm with some dirt before giving you
an injection, and recommend you eat your food on a floor instead of a plate.

Mate...

~~~
bryanlarsen
Bacteria, yes. For human cold & flu? Not so much. Not unless the dirt is where
humans congregate.

------
ecesena
Highly recommended TED talk:
[https://www.ted.com/talks/david_brenner_a_new_weapon_in_the_...](https://www.ted.com/talks/david_brenner_a_new_weapon_in_the_fight_against_superbugs)

And the longer interview:
[https://www.ted.com/talks/david_brenner_can_light_stop_the_c...](https://www.ted.com/talks/david_brenner_can_light_stop_the_coronavirus)

~~~
rtkaratekid
My first question is wouldn’t that cause strains of bacteria to develop UV
resistance? Otherwise it’s a pretty cool step forward

~~~
xkcd-sucks
High energy photons being what they are, at some point only more mass will
protect against it. The same reason 10 minutes of bleach exposire kills most
bacteria/virii but humans just get superficial burns.

i.e., it's easier for multicellular life to develop resistance to these kinds
of things than unicellular life

------
dreamcompiler
This is an important confirmation but it's not new. Researchers at Columbia
have been studying far UV on coronaviruses for a long time, and it's well-
established that far UV kills them.

The problem is that far UV lights are rather expensive at the moment.

[https://www.cuimc.columbia.edu/news/far-uvc-light-safely-
kil...](https://www.cuimc.columbia.edu/news/far-uvc-light-safely-kills-
airborne-coronaviruses)

~~~
2dvisio
Same here:
[https://www.nature.com/articles/s41598-020-67211-2](https://www.nature.com/articles/s41598-020-67211-2)

------
Vrondi
What distance from the surface can these lights be and still effectively kill
microorganism? 8 feet away? Or only a few centimeters?

~~~
jimsmart
I don't know the answer to your question, specifically.

But it might be helpful to know that the power/strength of light diminishes
according to the inverse-square law. That is, if one doubles the distance,
there is quarter the amount of light falling on a given area (vis: it is
quarter of the strength), and, vice versa, if one halves the distance, the
amount of light increases four-fold.

Due to this rate of fall-off, it means that it is much more effective if the
light source is closer.

------
exabrial
What portion of sunlight is 222nm?

~~~
zamfi
0% is also the non-pedantic answer:
[https://en.wikipedia.org/wiki/Sunlight](https://en.wikipedia.org/wiki/Sunlight)
and
[https://commons.wikimedia.org/wiki/File:Solar_spectrum_en.sv...](https://commons.wikimedia.org/wiki/File:Solar_spectrum_en.svg)

222nm is blocked by the (upper, I believe) atmosphere.

~~~
gonzo41
Just wait for all the deniers to start smashing lights. Hopefully this is a
nice easy way to safely deal with this issue. Combined with masks. It seems
like a way you could really clamp down.

------
alimw
To avoid confusing presidents a better title would be:

"Safer UV light effective in destroying virus particle associated with
transmission of Covid-19"

------
remote_phone
This was pretty much guaranteed. There were multiple studies showing that UVC
(not Far-UVC) quickly and effectively killed coronavirus. It was basically
just crossing the t’s and sorting the i’s to test Far-UVC light that it did
the same thing. But based on everything else it was obvious it would.

I’m hopeful we can see a lot of low cost Far-UVC appliances over the next year
that safely killed coronavirus in indoor places so that we can start living a
normal life before vaccines become widespread.

~~~
DenisM
There’s money to be made in spectrometers conforming proper spectrum of a
given device. The market will be flooded by cheap lights, and most of them
will be cutting every bit of cost to turn profit.

~~~
AstralStorm
222 nm UVC LEDs are cheap enough. Cost cutting is in number of them, power,
cooling and looks of the lamp.

~~~
ecesena
> 222 nm UVC LEDs are cheap enough

To my knowledge they don't exist yet. Do you know of any manufacturer that
produces them?

~~~
richajak
It does not have to be 222nm UVC, actually the most common ones available in
the market, 254nm, can also kill the virus. However, the researchers claim
that the 222nm is safer. This article is a bit sensational.

~~~
bwilli123
[https://sites.google.com/view/far-
uvccoronavirus/home](https://sites.google.com/view/far-uvccoronavirus/home)
[https://medi-immune.com/protectivair/](https://medi-immune.com/protectivair/)

------
d--b
How much exposure does it need?

~~~
sauwan
FTA:

>An in vitro experiment by HU researchers showed that 99.7% of the SARS-CoV-2
viral culture was killed after a 30-second exposure to 222 nm UVC irradiation
at 0.1 mW/cm2.

~~~
AstralStorm
This is slightly long to effectively remove the virus from air with people in
there breathing it.

It's good for an airlock or surface disinfection though.

~~~
Zancarius
30 seconds would be easy enough to fulfill for people queuing up at lines,
such as at a point of sale though. Sure, if you're standing next to someone
who's infected that's _probably_ not enough time, but combined with other
measures it might reduce the spread to others.

One of the studies that was investigating the use of hydroxychloroquine came
up with an interesting statistic that had nothing to do with HCQ: They found
that individuals with no PPE interacting at less than 6' from someone infected
with SARS-CoV-2 had about a 15% chance of contracting it after 10 minutes of
exposure. I'd imagine UV would reduce this even further.

This study was covered in Dr. Seheult's update 81[1] video. It's a bit ironic,
because the study showed a failure of HCQ, but I'm not _completely_ sure I'd
suggest the study itself failed since there's valuable insight that came as a
consequence of it!

[1]
[https://www.youtube.com/watch?v=o5w7FiDJe1g&t=2m32s](https://www.youtube.com/watch?v=o5w7FiDJe1g&t=2m32s)

~~~
caseysoftware
Is UV-C dangerous to people? If so, after how long?

It'd be interesting to consider this for doctor's waiting rooms, boarding
areas for planes & trains, and waiting areas for restaurants. Just waiting for
your table or appointment could sanitize you with zero additional effort. Not
100% but reducing the impact/risk in otherwise close quarter space would
reduce the overall spread.

~~~
Zancarius
The sibling comment posted to a general overview of UV light, but I think it's
a shame that it seems so dismissive. UVC, while higher frequency, can't
penetrate the outer layer of skin[1]. At low energies, I'd imagine it'd be
dangerous enough to virions and safe enough to humans for it to be a useful
area disinfectant.

Most of the studies I've seen use very low power sources that appear to be
fairly safe, but I'd imagine there's long term exposure risk.

Here's another article[2] worth reading. It appears to me that the specific
wavelengths most of the research has focused on is far-UVC which is _probably_
different from the frequencies of UVC currently more well studied.

So, I think the answer is "it depends."

[1] [https://www.klaran.com/is-uvc-safe](https://www.klaran.com/is-uvc-safe)

[2] [https://www.discovermagazine.com/health/are-ultraviolet-
sani...](https://www.discovermagazine.com/health/are-ultraviolet-sanitizing-
lights-safe-for-humans)

------
nograpes
Link to (paywalled?) article:

[https://doi.org/10.1016/j.ajic.2020.08.022](https://doi.org/10.1016/j.ajic.2020.08.022)

------
trident1000
Remember when people went ballistic when Trump suggested UV light therapy
could be a treatment. (probably still isnt but it was considered a scientific
impossibility that UV light does anything to a virus at the time).

~~~
triceratops
> it was considered a scientific impossibility that UV light does anything to
> a virus at the time

Citation required. UV light as a disinfectant is fairly well known.

It's not because he suggested UV light that people went ballistic. It's
because he suggested _shining it inside people 's bodies_. In that same press
conference he also suggested using bleach inside the body.

~~~
hiram112
He never used the word 'bleach'. Ironically, he used the word...
'disinfectant', as did you. The media started off the rumor of bleach, and
before you know it, his accurate statement was twisted into him telling people
to literally inject or guzzle bleach.

And you wonder why we call it fake news.

Here is the actual quote:

[https://www.statesman.com/news/20200713/fact-check-did-
trump...](https://www.statesman.com/news/20200713/fact-check-did-trump-tell-
people-to-drink-bleach-to-kill-coronavirus)

~~~
triceratops
You're right, he didn't explicitly say the word "bleach". Totally fake news
then, that's proved me an idiot that has. /s

In a briefing where they presented "a study that found sun exposure and
cleaning agents like bleach can kill the virus when it lingers on surfaces."
he suggested putting a "disinfectant" inside human bodies. Totally different
thing. Let's just use one of the other disinfectants that's safe to put inside
the body instead. [1] /s

It's fortunate that being a good communicator isn't one of the required skills
in his job. /s

I think your bar for calling something "fake" needs to be revised.

1\. [https://www.bbc.com/news/world-us-
canada-52407177](https://www.bbc.com/news/world-us-canada-52407177)

"Not only does consuming or injecting disinfectant risk poisoning and death,
it's not even likely to be effective.

Equally, by the time the virus has taken hold inside your body, no amount of
UV light on your skin is going to make a difference.

And since UV radiation damages the skin, using it to kill the virus could be a
case of - to borrow a well-worn phrase - the cure being worse than the
disease."

------
nimish
I mean, great? But sanitization doesn't seem to affect spread despite the
obsession over cleaning surfaces.

If the virus transmits in aerosols, as we have determined, does this 222nm
light kill that? No. It shows a smear of virus on a plate is killed by 222nm
light. I think it's the right solution for the wrong problem.

~~~
AstralStorm
Still useful for airlocks and perhaps disinfecting masks if tested on that.

------
DenisM
It’s quite exciting - replacing existing overhead lighting with 222nm
lightbulbs could make public spaces inhabitable again.

Alas I couldn’t find any 222nm light bulbs for sale. I imagine hundreds of
Chinese companies are setting up production lines as we speak.

