what's a quick way to verify UVC from germicidal lamp?

[KC JONES]

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick. However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

 

[John Robertson]

On 2020/01/18 1:11 p.m., KC JONES wrote:

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick.  However, I don't know if it still emits the germ killing
UVC spectrum.  What's a quick way I could tell for sure?  Thanks.

Inverse square law makes your idea not so practical, aside from the
inherent dangers of exposure to raw UV light!

Better to wash the room down with a disinfectant, or simply air it out
for a while...

If the person was very contagious then look up the procedures for
dealing with that rather than making up your own potentially dangerous
ones.

John :-#(#

 

[JBI]

On 1/18/20 5:08 PM, John Robertson wrote:

On 2020/01/18 1:11 p.m., KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick.  However, I don't know if it still emits the germ
killing UVC spectrum.  What's a quick way I could tell for sure?  Thanks.

Inverse square law makes your idea not so practical, aside from the
inherent dangers of exposure to raw UV light!

I'm well aware of this after having used such lamps in the past.

Better to wash the room down with a disinfectant, or simply air it out
for a while...

The problem is that there are dogs and cats present and the room I want
to sterilize is in a relative's house. They own the pets, but I haven't
had a pet in over 40 years. If I were disinfecting my own room, I might
use 70% iso rubbing alcohol in sprayer format or even a weak bleach
solution, but animals pretty much rule out either chemical. At least
with the lamp, there are no residuals other than perhaps weak ozone that
can be aired out quickly.

If the person was very contagious then look up the procedures for
dealing with that rather than making up your own potentially dangerous
ones.

Trying not to make this complicated. All I wanted to do was see if the
lamp was in fact still producing the necessary UVC spectrum. Surely,
there should be something on the market that perhaps fluoresces only
when UVC illuminates it. Or something similar and relatively simple.

John :-#(#

 

[pfjw@aol.com]

a) Neither cats nor dogs are threatened by a low concentration of either bleach or isopropyl alcohol.
b) Anything over 10% alcohol or 0.5% sodium hypochlorite is an effective germicide & viricide.
c) Common 80-proof Vodka cut 4:1 is also very effective, and leaves no residue.

With that in mind, and the exposure requirements for UV to be effective, you would be far better served to use an alcohol solution. Which has the additional virtue of being able to get behind and into cracks and corners where light will not.

Do also research the viability of the infections involved over time, tolerance of temperature extremes, tolerance of humidity extremes and so forth. And, just for giggles, look up Hospital patient room discharge requirements.

Peter Wieck
Melrose Park, PA

 

[amdx]

On 1/18/2020 3:11 PM, KC JONES wrote:

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick.  However, I don't know if it still emits the germ killing
UVC spectrum.  What's a quick way I could tell for sure?  Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC bulbs
so I need to ask is does yours have a specific wavelength output? Like
270nm? My limited search finds bulbs of 254nm to 270 nm.
I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if it
senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

Mikek

 

[amdx]

On 1/19/2020 8:59 AM, amdx wrote:

On 1/18/2020 3:11 PM, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick.  However, I don't know if it still emits the germ
killing UVC spectrum.  What's a quick way I could tell for sure?  Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC bulbs
so I need to ask is does yours have a specific wavelength output? Like
270nm? My limited search finds bulbs of 254nm to 270 nm.
 I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
 Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if it
senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

                                      Mikek

I should have posted the sensor.
> https://cdn-shop.adafruit.com/datasheets/1918guva.pdf

and the adafruit pcb.

> https://www.adafruit.com/product/1918?gclid=Cj0KCQiAmZDxBRDIARIsABnkbYTW4uwwxg5rvIcjY6z2MlUDvmN4QcL5PgAGeBvgHixbOqSlqbiXfFMaAn90EALw_wcB

 

[Ralph Mowery]

In article <r00ufh$et2$1@dont-email.me>, JBI@ez1.net says...

Trying not to make this complicated. All I wanted to do was see if the
lamp was in fact still producing the necessary UVC spectrum. Surely,
there should be something on the market that perhaps fluoresces only
when UVC illuminates it. Or something similar and relatively simple.

Lots of cloth material made out of polyester that is white will have a
chemical in it that glows under the UV light.

Try taking several pieces of white clothing and even the white thread
that some buttons are sewen on with will work.

Where I worked making polyester sandoze was added to the material to
make the whites even whiter. That glows under UV light.

 

[Allodoxaphobia]

On Sun, 19 Jan 2020 10:08:04 -0500, Ralph Mowery wrote:

In article <r00ufh$et2$1@dont-email.me>, JBI@ez1.net says...

Trying not to make this complicated. All I wanted to do was see if the
lamp was in fact still producing the necessary UVC spectrum. Surely,
there should be something on the market that perhaps fluoresces only
when UVC illuminates it. Or something similar and relatively simple.

Lots of cloth material made out of polyester that is white will have a
chemical in it that glows under the UV light.

Try taking several pieces of white clothing and even the white thread
that some buttons are sewen on with will work.

Where I worked making polyester sandoze was added to the material to
make the whites even whiter. That glows under UV light.

Cat piss. Cat piss shows up quite bright under UV light.

Glad to help,
Jonesy
--
Marvin L Jones | Marvin | W3DHJ.net | linux
38.238N 104.547W | @ jonz.net | Jonesy | FreeBSD
* Killfiling google & XXXXbanter.com: jonz.net/ng.htm

 

[Jeff Liebermann]

On Sat, 18 Jan 2020 16:11:01 -0500, KC JONES <kcharlie@nowhere.net>
wrote:

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick. However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

Ummm... perhaps a UV-C light meter? Something like this:
<https://www.solarmeter.com/uvc-meters.html>
<https://youtu.be/6Jaic8OwzaU>
Response is 246-262 nm with a UV-C pass filter.

More of the same:
<https://www.ebay.com/sch/i.html?_nkw=uvc+light+meter>
Typically $350 to $1,100. You might want to look into borrowing or
renting such a meter.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Ralph Mowery]

In article <04k92fhqd6l2ekn8gdfbhjqq3cug1r31cp@4ax.com>,
jeffl@cruzio.com says...

More of the same:
https://www.ebay.com/sch/i.html?_nkw=uvc+light+meter
Typically $350 to $1,100. You might want to look into borrowing or
renting such a meter.

You would think that China would have some for way under $50 . While
they may not work the best, China seems to have almost every thing else
very inexpensive.

Bad to pay $ 300 + to check out a $ 20 or so light.

 

[Jeff Liebermann]

On Sun, 19 Jan 2020 19:01:47 -0500, Ralph Mowery
<rmowery28146@earthlink.net> wrote:

In article <04k92fhqd6l2ekn8gdfbhjqq3cug1r31cp@4ax.com>,
jeffl@cruzio.com says...

More of the same:
https://www.ebay.com/sch/i.html?_nkw=uvc+light+meter
Typically $350 to $1,100. You might want to look into borrowing or
renting such a meter.

You would think that China would have some for way under $50 . While
they may not work the best, China seems to have almost every thing else
very inexpensive.

Bad to pay $ 300 + to check out a $ 20 or so light.

I couldn't find anything from China that is substantially cheaper:
<https://www.aliexpress.com/wholesale?trafficChannel=main&d=y&SearchText=uvc+meter&ltype=wholesale&SortType=price_asc&groupsort=1&CatId=0&page=1>

The bulk of the cost seems to be in the sensor and the UV-C filter.
<https://www.aliexpress.com/item/32998762871.html>
<https://www.edmundoptics.com/c/optical-filters/610/#27587=27587_d%3A%5B200.00%20TO%20280.00%5D&ProductFamilies_ii=ProductFamilies_ii%3AMTQ5NjM1>

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[whit3rd]

On Sunday, January 19, 2020 at 2:18:04 PM UTC-8, Jeff Liebermann wrote:

On Sat, 18 Jan 2020 16:11:01 -0500, KC JONES <kcharlie@nowhere.net
wrote:

I've had a germicidal lamp more or less in storage...However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

Ummm... perhaps a UV-C light meter?
Typically $350 to $1,100. You might want to look into borrowing or
renting such a meter.

It'll embrittle plastic quick if it's really UV-C; a disposable bag turning to
dust would convince me it was shining. Or, you could imagine something with
a slit, telescope mirror, thermopile, and grating, if intensity measurement was
important.

I'd think of something quick-and-dirty before shelling out bucks.

 

[pfjw@aol.com]

Not so long ago, someone here stated that this group exists to teach gullible individuals how to do things the hard way (as opposed to the correct way, or the effective way. Emphatically not the 'easy way').

This thread is a very nearly perfect example of that process.

a) Whereas light on the correct UV spectrum *will* kill many (not all) microbes and such, it is not designed against the stated purpose. As an Ozonator in a water sterilization device, fine. Or in a fume-hood.

NOTE FROM SECONDARY SOURCE: Germicidal lamps emit radiation in the UV-C portion of the ultraviolet (UV) spectrum, which includes wavelengths between 100 and 280 nanometers (nm). The lamps are used in a variety of applications where disinfection is the primary concern, including air and water purification, food and beverage protection, and sterilization of sensitive tools such as medical instruments. Germicidal light destroys the ability of bacteria, viruses, and other pathogens to multiply by deactivating their reproductive capabilities. The average bacteria may be killed in 10 seconds at a distance of 6 inches from the lamp.

b) That form of UVR that is effective in killing pathogens will also damage humans.

NOTE FROM SECONDARY SOURCE: UVR is not felt immediately; in fact, the user may not realize the danger until after the exposure has caused damage. Symptoms typically occur 4 to 24 hours after exposure. The effects on skin are of two types: acute and chronic. Acute effects appear within a few hours of exposure, while chronic effects are long-lasting and cumulative and may not appear for years. An acute effect of UVR is redness of the skin called erythema (similar to sunburn). Chronic effects include accelerated skin aging and skin cancer. UVR is absorbed in the outer layers of the eye – the cornea and conjunctiva. Acute overexposure leads to a painful temporary inflammation, mainly of the cornea, known as photokeratitis. Subsequent overexposure to the UV is unlikely because of the pain involved. Chronic exposure leads to an increased risk of certain types of ocular cataracts.
Working unprotected for even a few minutes can cause injury. It is possible to calculate the threshold for acute effects and to set exposure limits. It is not possible, however, to calculate threshold for chronic effects; therefore, because no exposure level is safe, exposure should be
reduced as much as possible.

c) If one takes the 30 seconds or so to research how UV light is used in laboratory settings to sterilize equipment, surfaces and instruments, one will see that, again, it is not indicated for the purpose stated hear.

Bottom line: UV light is not indicated. UV light is dangerous. UV light is not 'quick' either. To do what is required per the OP is good old 'asses and elbows' work, not the waving of a magic wand or, pun intended, light saber.

Put another way: There are two issues here: #1 is the sterilizing of a sick-room after the fact. For which UV light is neither safe nor effective. #2 is to determine if any given UV lamp is still emitting over the target frequency(ies). And that may be had right off the shelf, cheap:

https://www.teachersource.com/product/1099/light-ultraviolet?gclid=Cj0KCQiAvJXxBRCeARIsAMSkApqY9BBWjslaJA5PLzVT7qnP36iVSDKkQ2tk8DbdCzk909RKYiYm76kaAvyVEALw_wcB

https://www.amazon.com/JPSOR-Scientific-Changing-Reactive-Plastic/dp/B01LZFI7AF/ref=asc_df_B01LZFI7AF/?tag=hyprod-20&linkCode=df0&hvadid=198064277648&hvpos=1o3&hvnetw=g&hvrand=12129056433328399856&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9007324&hvtargid=pla-350869888021&psc=1

And thousands (yes, thousands) of other sources.

Peter Wieck
Melrose Park, PA

 

[Stephen Wolstenholme]

On Sat, 18 Jan 2020 16:11:01 -0500, KC JONES <kcharlie@nowhere.net>
wrote:

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick. However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

All the UVC lights I have ever used have some part of the visible
spectrum. See if white items "glow".

Steve

--
http://www.npsnn.com

 

[amdx]

On 1/19/2020 9:01 AM, amdx wrote:

On 1/19/2020 8:59 AM, amdx wrote:
On 1/18/2020 3:11 PM, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick.  However, I don't know if it still emits the germ
killing UVC spectrum.  What's a quick way I could tell for sure?
Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC bulbs
so I need to ask is does yours have a specific wavelength output? Like
270nm? My limited search finds bulbs of 254nm to 270 nm.
  I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
  Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if it
senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

                                       Mikek

 I should have posted the sensor.
https://cdn-shop.adafruit.com/datasheets/1918guva.pdf

 and the adafruit pcb.

https://www.adafruit.com/product/1918?gclid=Cj0KCQiAmZDxBRDIARIsABnkbYTW4uwwxg5rvIcjY6z2MlUDvmN4QcL5PgAGeBvgHixbOqSlqbiXfFMaAn90EALw_wcB

No one has responded to my post. Is there anything fundamentally wrong
other than the cost of filters is high and the sensor has it weakest
response in the UVC wavelength.
I don't mind the idea getting shot down, I'd learn something.

Mikek

 

[John Robertson]

On 2020/01/20 6:23 p.m., amdx wrote:

On 1/19/2020 9:01 AM, amdx wrote:
On 1/19/2020 8:59 AM, amdx wrote:
On 1/18/2020 3:11 PM, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a
person had been sick.  However, I don't know if it still emits the
germ killing UVC spectrum.  What's a quick way I could tell for
sure? Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC
bulbs so I need to ask is does yours have a specific wavelength
output? Like 270nm? My limited search finds bulbs of 254nm to 270 nm.
  I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
  Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if
it senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

                                       Mikek

  I should have posted the sensor.
https://cdn-shop.adafruit.com/datasheets/1918guva.pdf

  and the adafruit pcb.

https://www.adafruit.com/product/1918?gclid=Cj0KCQiAmZDxBRDIARIsABnkbYTW4uwwxg5rvIcjY6z2MlUDvmN4QcL5PgAGeBvgHixbOqSlqbiXfFMaAn90EALw_wcB




 No one has responded to my post. Is there anything fundamentally wrong
other than the cost of filters is high and the sensor has it weakest
response in the UVC wavelength.
 I don't mind the idea getting shot down, I'd learn something.

                                       Mikek

Hi Mikek,

While your information may be valid, it is of little use to the OP to
try to use a UV bulb to sterilize the room. It would be dangerous to his
eyes and or skin, and it would be ineffective as the UV only would
effect microbes that are on a surface the UV light would strike, plus
the UV light has to be near (under 1 foot typically) to have a high
enough concentration and it needs to light up the organisms for up to
five minutes to be sure of killing them. Thus you have to hold the UV
lamp for five minutes over every square inch of the room and you won't
get any of the crevasses at all!

So totally impractical.

On the other hand if you made a separate posting under the topic of
tools to measure UV bandwidth (or similar) you might get more bites!

John :-#)#

 

On Monday, January 20, 2020 at 10:29:31 PM UTC-5, John Robertson wrote:

On 2020/01/20 6:23 p.m., amdx wrote:
On 1/19/2020 9:01 AM, amdx wrote:
On 1/19/2020 8:59 AM, amdx wrote:
On 1/18/2020 3:11 PM, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a
person had been sick.  However, I don't know if it still emits the
germ killing UVC spectrum.  What's a quick way I could tell for
sure? Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC
bulbs so I need to ask is does yours have a specific wavelength
output? Like 270nm? My limited search finds bulbs of 254nm to 270 nm.
  I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
  Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if
it senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

                                       Mikek

  I should have posted the sensor.
https://cdn-shop.adafruit.com/datasheets/1918guva.pdf

  and the adafruit pcb.

https://www.adafruit.com/product/1918?gclid=Cj0KCQiAmZDxBRDIARIsABnkbYTW4uwwxg5rvIcjY6z2MlUDvmN4QcL5PgAGeBvgHixbOqSlqbiXfFMaAn90EALw_wcB




 No one has responded to my post. Is there anything fundamentally wrong
other than the cost of filters is high and the sensor has it weakest
response in the UVC wavelength.
 I don't mind the idea getting shot down, I'd learn something.

                                       Mikek

Hi Mikek,

While your information may be valid, it is of little use to the OP to
try to use a UV bulb to sterilize the room. It would be dangerous to his
eyes and or skin, and it would be ineffective as the UV only would
effect microbes that are on a surface the UV light would strike, plus
the UV light has to be near (under 1 foot typically) to have a high
enough concentration and it needs to light up the organisms for up to
five minutes to be sure of killing them. Thus you have to hold the UV
lamp for five minutes over every square inch of the room and you won't
get any of the crevasses at all!

So totally impractical.

On the other hand if you made a separate posting under the topic of
tools to measure UV bandwidth (or similar) you might get more bites!

On some work sites, you see the plumbers or steamfitters welding (tig) black iron pipe, creating light that could hurt the cornea of un-protected eyes.. How would germs stand up to that spectrum? You have to wonder.

 

[John Robertson]

On 2020/01/21 10:33 a.m., bruce2bowser@gmail.com wrote:

On Monday, January 20, 2020 at 10:29:31 PM UTC-5, John Robertson wrote:
On 2020/01/20 6:23 p.m., amdx wrote:
On 1/19/2020 9:01 AM, amdx wrote:
On 1/19/2020 8:59 AM, amdx wrote:
On 1/18/2020 3:11 PM, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a
person had been sick.  However, I don't know if it still emits the
germ killing UVC spectrum.  What's a quick way I could tell for
sure? Thanks.

I see UVC covers 200nm to 280nm. I don't know anything about UVC
bulbs so I need to ask is does yours have a specific wavelength
output? Like 270nm? My limited search finds bulbs of 254nm to 270 nm.
  I did a little searching and didn't find anything in the way of UVC
sensors. But maybe a way to back into it?
  Adafruit has a UV sensor that works from 240nm to 370nm for $6.50.
Maybe buy a filter for UVA and UVB, to cover that sensor and see if
it senses any UVC. OR buy a UVC sensor and flip flop covering and
uncovering the sensor and see if you get a square wave output.

                                       Mikek

  I should have posted the sensor.
https://cdn-shop.adafruit.com/datasheets/1918guva.pdf

  and the adafruit pcb.

https://www.adafruit.com/product/1918?gclid=Cj0KCQiAmZDxBRDIARIsABnkbYTW4uwwxg5rvIcjY6z2MlUDvmN4QcL5PgAGeBvgHixbOqSlqbiXfFMaAn90EALw_wcB




 No one has responded to my post. Is there anything fundamentally wrong
other than the cost of filters is high and the sensor has it weakest
response in the UVC wavelength.
 I don't mind the idea getting shot down, I'd learn something.

                                       Mikek

Hi Mikek,

While your information may be valid, it is of little use to the OP to
try to use a UV bulb to sterilize the room. It would be dangerous to his
eyes and or skin, and it would be ineffective as the UV only would
effect microbes that are on a surface the UV light would strike, plus
the UV light has to be near (under 1 foot typically) to have a high
enough concentration and it needs to light up the organisms for up to
five minutes to be sure of killing them. Thus you have to hold the UV
lamp for five minutes over every square inch of the room and you won't
get any of the crevasses at all!

So totally impractical.

On the other hand if you made a separate posting under the topic of
tools to measure UV bandwidth (or similar) you might get more bites!

On some work sites, you see the plumbers or steamfitters welding (tig) black iron pipe, creating light that could hurt the cornea of un-protected eyes.. How would germs stand up to that spectrum? You have to wonder.

Welding light is very dangerous, but the OP was talking about a
fluorescent UV sterilizing lamp. Completely different levels of intensity.

One could as easily say a nuclear bomb (or the surface of the Sun) is
hard on bacteria...

John :-#)#

 

[Tim R]

On Saturday, January 18, 2020 at 4:11:06 PM UTC-5, KC JONES wrote:

I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick. However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

It's a good question (if not a good use.) Amazon is full of air purifiers that include UV light inside the enclosure. That light must degrade over time, if it even works at all.

A quick google says change the bulb every 12 months. I bet it isn't cheap, either.

So, A your lamp probably kills germs for about 6 inches, and B it's probably worn out by now anyway.

 

[Tim R]

On Tuesday, January 21, 2020 at 2:43:01 PM UTC-5, Tim R wrote:

On Saturday, January 18, 2020 at 4:11:06 PM UTC-5, KC JONES wrote:
I've had a germicidal lamp more or less in storage for a number of
years, but recently brought it out to sterilize a room where a person
had been sick. However, I don't know if it still emits the germ killing
UVC spectrum. What's a quick way I could tell for sure? Thanks.

It's a good question (if not a good use.) Amazon is full of air purifiers that include UV light inside the enclosure. That light must degrade over time, if it even works at all.

A quick google says change the bulb every 12 months. I bet it isn't cheap, either.

So, A your lamp probably kills germs for about 6 inches, and B it's probably worn out by now anyway.

Snip from a UV website:
********
What distance and how long would I have to expose an article to germicidal ultraviolet to sanitize it?
The exposure necessary to inactivate microorganisms is a product of time and ultraviolet intensity. High intensities for a short period of time, or low intensities for a long period of time are fundamentally equal in lethal action on infectious microorganisms. As a rule of thumb, at two inches away from the STER-L-RAY ÂŽ germicidal ultraviolet lamp, most common bacteria and virus are inactivated within five seconds of exposure. For specific recommendations, please call our staff with the details of your application (including area available for the fixture, how far the fixture will be from the article, etc.) The more information you can provide, the better.