
Can you kill coronavirus with UV light? - tartoran
https://www.bbc.com/future/article/20200327-can-you-kill-coronavirus-with-uv-light
======
devy
The simple answer is it probably can, but the actual facts are more nuanced
than a simple confirmation.

All bio-safety labs or hospitals or water treatment plants or special HVAC
systems have UV-C lamps to sanitize pathogens because UV-C radiation
destroying nucleic acids (DNAs / RNAs).[1] However, the effectiveness really
depends on the amount exposure/energy level, light of sight(because UV-C
doesn't penetrate deep into objects), and even dust in the air or the on the
UV-C light lamps(which reduced the energy they emit) as well as how DNA/RNA
can be evolved or self-repaired.

Anecdotally, Chinese hospitals are using UV-C lamp to sanitize their medical
equipments, masks (when it was in short supply months ago) among other things.

And yes, more exhaustive experiments should be conducted to affirm this
practice as it's the most non-toxic and energy efficient way to sanitize
surfaces.

[1]:
[https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradia...](https://en.wikipedia.org/wiki/Ultraviolet_germicidal_irradiation)

[2]: [https://www.cnbc.com/2020/03/18/how-china-is-using-robots-
an...](https://www.cnbc.com/2020/03/18/how-china-is-using-robots-and-
telemedicine-to-combat-the-coronavirus.html)

~~~
dillonmckay
All water treatment plants do not use UV.

It is actually fairly expensive.

Some municipalities only use chlorine. My municipality only has a 40 day
supply of chlorine to treat the water.

For such reasons, I purchased a whole-home UV-C water unit.

Now, the wastewater plant uses UV-C, but its output is cleaner than the
drinking water input (river).

~~~
Scoundreller
Can also use ozone. One of Toronto's plants uses it and treats about 20% of
the city's water. Nice thing is that you don't need railcars to arrive with
it.

[https://www.toronto.ca/services-payments/water-
environment/t...](https://www.toronto.ca/services-payments/water-
environment/tap-water-in-toronto/fast-facts-about-the-citys-water-treatment-
plants/)

~~~
m-p-3
And I believe a byproduct of UV irradiation is the generation of ozone.

------
ebg13
Yes AND, despite the mongering in this article, UVC wavelengths below 222nm
have been found to be safe to mammalian skin.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552051/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5552051/)

[https://journals.plos.org/plosone/article?id=10.1371/journal...](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201259)

~~~
jiofih
From the linked paper:

> the effect of chronic irradiation with a high dose of 222-nm UVC to
> mammalian cells has not been determined

Please be careful in announcing new truths based on your interpretation of a
couple papers. That’s not how science is done.

~~~
ebg13
You're misinterpreting that sentence. They are talking about data missing from
_prior_ work there.

The title of the article is literally "Chronic irradiation with 222-nm UVC
light induces neither DNA damage nor epidermal lesions" and a few sentences
below the discussion of prior work they write "chronic irradiation with 222-nm
UVC light was revealed not to induce mutagenic or cytotoxic effects in the
epidermis".

~~~
jiofih
> of rats

------
Confiks
Has anyone found anything on the health implications of mounting 220nm lamps
[1] indoors, _beyond_ the issue of damaging human DNA? In other words, if you
assume those lamps to be safe to living cells due to the light not penetrating
beyond the first layer of dead skin cells, what other problems might there be?

Our skin surface contains a lot of living bacteria. Different strains seem
compete with each other, and for example an overgrowth of staphylococcus
aureus seems to be correlated with skin issues. In that sense living bacteria
protect our skin. How would an far-UVC 'antibiotic' lamp influence bacterial
repopulation later? Either on skin and in spaces. Would it impair immune
system development?

Viruses seem far more fragile than bacteria, so perhaps a low-power far UVC-
lamp will be enough to kill viruses but leave the bacterial populations on
skin and objects intact

[1]
[https://www.nature.com/articles/s41598-018-21058-w](https://www.nature.com/articles/s41598-018-21058-w)

~~~
fabian2k
You get a nasty sunburn from resonably strong UV lamps. I've seen that happen
with people being very careless in the lab when using a UV bed for gel
electrophoresis.

These are UV lamps strong enough to visualize ethidium bromide, I'm not even
sure if they're strong enough to kill bacteria quickly, though I'd guess they
might be. UV lamps are really not something you should point at humans.

~~~
RL_Quine
It also burns your retinas and produces ozone.

~~~
CamperBob2
No optical damage in this wavelength range (although the ozone may still be an
issue.)

Suggest reading the articles people have linked to in this thread, pretty
interesting stuff. I had no idea that there was a portion of the UVC spectrum
that doesn't have significant harmful effects on humans.

~~~
godelski
UV definitely can damage the eyes. I suspect what the paper meant is not the
wavelength, but the power. Because UV also burns skin. I've seen it happen.
Both power and wavelength matter.

~~~
toomuchtodo
Far-UVC deactivates pathogens without causing damage to skin or eye tissue.

------
blackhaz
I have ordered a 15 W Chinese E27 UVC (200-275 nm) lamp from Amazon, and a E27
to wall socket plug with remote control. I am going to place it in the
quarantine zone downstairs to zap incoming mail and packages, just for any
case.

In one SARS-CoV study [1] the authors have irradiated SARS-CoV with a 254 and
365 nm UVC-UVA light source that emitted 4016 μW/cm^2. They found that
"exposure of virus to UVC light resulted in partial inactivation at 1 min with
increasing efficiency up to 6 min (Fig. 1A), resulting in a 400-fold decrease
in infectious virus."

If my math is correct, a 15 Watt UVC light bulb will provide 4.77 W/m^2 flux
within the radius of 0.5 m - assuming it emits omnidirectionally. Assuming the
delivered power versus inactivation efficiency relationship is linear, it
would require roughly about an hour of zapping to achieve the same levels of
inactivation with a 15 W lamp.

Yes, we don't know if SARS-CoV inactivation times are comparable to that of
COVID-19, but it's better than nothing. I am not a biologist, and micrographs
of both viruses look somewhat similar. I wonder if they are structurally
similar, should we expect similar susceptibility to incoming UV photons?

[1] [https://medtradex.com/assets/Uploads/Literature-UVD-
Corona.p...](https://medtradex.com/assets/Uploads/Literature-UVD-Corona.pdf)

~~~
lvturner
Would you mind linking to the light you bought? Or a comparable one l.

~~~
blackhaz
Here is the one. I don't know if it performs in spec. Never bought one before.

[https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt...](https://www.amazon.co.uk/gp/product/B085HZK755/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1)

~~~
walterbell
Because this is (a) NOT Far-UVC, and (b) 360-degree light that shines in all
directions, the only way to use it safely is with a remote power switch or a
short timer so you (and pets) can get out of the room before the light turns
on. Don't re-enter the room until the light is switched off remotely or with a
timer. It is hazardous to your eyes and skin.

Could it be used in a spotlight lamp that directs all the light in one
direction?

~~~
jennyyang
I mention below I place the light bulb (using a hand-held socket) in a glass
aquarium. Glass completely blocks UV-C light. The other hazard is ozone, so I
use this outdoors on my patio or garage.

~~~
nerfhammer
> Glass completely blocks UV-C light.

Erm, then why do they come in glass tubes like florescent lights?

~~~
augustt
Not all glass is the same. Pure silica glass will pass UV, the soda-lime glass
your windows are made of won't.

------
tzs
Slightly OT: numerous sources say that if the virus is on a surface, it
eventually dies (or deactivates anyway, if you don't consider viruses alive in
the first place). It can last up to 4 days on glass, 3 on steel and plastic,
and 24 hours on cardboard.

What I've not seen explained and have no guess for is _why_ it deactivates. It
doesn't have a metabolism. It doesn't consume resources or use energy. It just
sits there, a little spiky spheroid surrounding some fragments of DNA or RNA.

So what changes about it as it sits that causes it to deactivate?

~~~
guardiangod
[https://www.marketwatch.com/story/deadly-viruses-are-no-
matc...](https://www.marketwatch.com/story/deadly-viruses-are-no-match-for-
plain-old-soap-heres-the-science-behind-it-2020-03-08)

 _So why are surfaces different? The virus is held together by a combination
of hydrogen bonds (like those in water) and hydrophilic, or “fat-like,”
interactions. The surface of fibers or wood, for instance, can form a lot of
hydrogen bonds with the virus.

In contrast, steel, porcelain or Teflon do not form much of a hydrogen bond
with the virus. So the virus is not strongly bound to those surfaces and is
quite stable._

~~~
dreamcompiler
I linked Thordarson's Twitter thread on the subject above. Didn't know he'd
written an article too. Nice!

------
herf
For anyone who's interested, CIE recently made their UVGI standards available
for free ($150 normally):

[http://files.cie.co.at/cie187-2010%20(free%20copy%20March%20...](http://files.cie.co.at/cie187-2010%20\(free%20copy%20March%202020\).pdf)
[http://files.cie.co.at/cie155-2003%20(free%20copy%20March%20...](http://files.cie.co.at/cie155-2003%20\(free%20copy%20March%202020\).pdf)

Generally you don't want to be around most UVC (253nm) because these
wavelengths are very good at giving you cataracts, etc. So if you buy these
things online, don't stay in the room when you turn them on.

There are some newer lamps (210-220nm) that don't seem to penetrate the outer
layer of the epidermis (cornea or skin) and so might be OK for occupied
spaces. But companies are still being very cautious about occupied uses,
because this all still has yet to be proven in real life. Also, 220nm requires
excimer lamps, so 253nm is way easier to get for now.

~~~
prox
How about just heating your mail in a dry oven? Thats what Stanford tested for
PPE masks.

Or just waiting 24 hours or more works as well,

------
nimbius
hey! relevant anecdotal data here. I work in an automotive repair garage.
Anyone who has to drive a vehicle dropped off by a customer has to make sure
its been UV sanitized first. We drape a 40 watt CFL UV lamp from your rearview
mirror, put your floor mats on your windshield and rear window, and cover the
windows with scratch mats for 35 minutes. After the timer goes off, a big blue
sticker goes on your window. We then do it all over again before we give the
truck or car back to you.

We had 2 ozone generators we were using (normally to remove cigarette smoke
from car seats) but they take hours. the bulbs are cheaper and faster!!

------
perl4ever
I'm not running out to get any sort of UV lamp now but I am mildly interested
in a thing I heard about that works with forced air ducting in a home
AC/heating system. Not sure if it would help with allergies.

------
augustt
Does anyone know how LED-based UVC lamps like [1] with >300 LEDs can sell on
Amazon for less than $100 when it appears the individual LEDs are fairly
expensive? On DigiKey/Mouser the cheapest price I can find is still more than
$1/LED [2].

[1] [https://www.amazon.com/2020-Newest-Germicidal-Lamp-
Light/dp/...](https://www.amazon.com/2020-Newest-Germicidal-Lamp-
Light/dp/B085VWPT9C/ref=sr_1_1_sspa?dchild=1&keywords=germicidal+lamp&qid=1585434962&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExTFFKUzMwMURPNzAzJmVuY3J5cHRlZElkPUEwNjg0NjE3MzlJNE9aV0xWM1M5VCZlbmNyeXB0ZWRBZElkPUEwNjQzMzkyM1ExQ0QxWkZVR09DJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==)

[2] [https://www.mouser.com/Optoelectronics/LED-Lighting/LED-
Emit...](https://www.mouser.com/Optoelectronics/LED-Lighting/LED-
Emitters/_/N-8usfd?P=1y962egZ1y8pnoeZ1y8tivpZ1y97r6q&Ns=Pricing|0)

~~~
nerfhammer
Curious, I didn't even know they made UV-C leds yet. Normal UV leds are UV-A.

Otherwise digikey/mouser prices for LEDs are usually exorbitant. Try Chinese
marketplace sites instead.

------
sjg007
Yeah I would expect a rise in HVAC installations. I was surprised that cruise
ships don’t have them installed along with hepa filters.

~~~
wool_gather
Interesting; is this a current practice? How do you get enough exposure time
to be effective in moving air?

~~~
mensetmanusman
By integrating over distance :)

------
makomk
Big Clive over on YouTube was complaining the other day that certain sellers
of these lights had taken part of his video warning against exposing skin to
them and used it to claim they were skin-safe when promoting them for use
against the coronavirus. It was some way into a multi-hour livestream, so I'm
not going to try and dig it out though.

------
smileysteve
This is a pretty sham conclusion. "No" if you use where people are. No mention
of the utility in cleaning areas that are temporarily closed to the public.

Light hits a lot more surface than just you are spraying and wiping.

In things like grocery stores being cleaned every night; or even with modern
proximity sensors being able to turn on a 5 min burst of uv-c without anybody
in the room. Uv-c (while yes requiring precautions) should work great.

I happened to have bought a uvc wand in November. It has a button and tilt
sensor so it's hard to accidentally scan over your eyes. It's definitely
reassuring to "wipe" the phone and door handles when I come back in the house
at close proximity for a few seconds.

------
sakoht
It's sad that even the BBC allows people who don't know what they are talking
about to spread propaganda, not even knowing it. It kills everything the size
of a virus because of its size, not some magical attributes the virus may or
may not have. The other comments show three recent scientific publications in
top-tier journals showing the narrow wavelength (222nm) that doesn't harm
human skin or eyes.

~~~
whatshisface
> _It kills everything the size of a virus because of its size, not some
> magical attributes the virus may or may not have._

It wouldn't cause a tiny iron sphere to disintegrate. It's not true that
everything the size of a coronavirus can be "messed up" by UV light.

------
tiku
Time for led bulbs that also contain uvc light, perhaps with a battery so that
you can clean a room after you turn of the light.

------
mrfusion
I’ve always wondered. Why can’t we put uv lamps in Hvac air handlers?
Especially on airplanes and cruise ships.

I guess before there was no compelling reason to have the extra cost but now
it might be time to rethink it.

~~~
techsupporter
We can. Half a lifetime ago, I replaced the HVAC in my house and one of the
add-ons, which I bought, was a UV disinfecting lamp.

I have no idea if it was effective or snake oil but it was on offer. Hospitals
and medical labs have (demonstrably effective) UV lights in their HVAC
systems.

------
outlace
Is it the seasonal changes in UV that make flu and similar viruses less
transmissible during the summer months? Maybe it has nothing to do with
temperature as some have suggested.

~~~
chrisco255
It's been argued that both temperature and humidity make viruses less
transmissible. Not sure about the UV intensity.

------
randomsearch
Question for biologists, doctors etc:

AFAIK we don’t understand why “flu season” ends.

Is it not likely that increased UV in spring/summer may tip the balance? Has
this explanation been proved/disproved?

------
pcvarmint
Zinc works better than UV light, and has fewer side effects.

------
Giorgi
So article says: "No" and then goes on to describe how it kills virus. WTF

~~~
downerending
Crappy headlines are a major form of fake news.

(I wrote to a major paper once to complain about this, and the author of the
article replied: _Well, I don 't write the headlines._ Hooray.)

~~~
a3n
I wrote to the Denver Post once, and the editor replied "We don't write the
articles." It was a local story, but written by the paper's owning entity, for
publication in all of its owned papers, including the Post where the incident
happened. I guess sort of like an in-house news wire "service."

They do obviously write some of the articles that appear in their paper.

