Talk:Ultraviolet germicidal irradiation

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Article merged: See old talk-pages here and here

Propaganda

This article is mere propaganda, and does not deserve to be on Wikipedia's Main Page. UV's main drawback is its lack of a residual, meaning that any germ that by chance survives the radiation, can begin to reproduce happily in the piping system once this single hurdle of UV radiation is taken. The odds of survival are in fact quite high, because the radiation intensity decreases exponentially an a straight path, being further attenuated fpr spatial reasons (radial rather than parallel light beams), so that many commercial systems contain lines through which germs could theoretically pass rather unharmed. In fact, I have seen commercial systems where after the UV system the germ count was higher than before, owing to biofilm development at the exit parts that are not exposed to radiation, and where because of tha lack of a residual, there is no disinfection at all. In addition, "real" water contains lots of material that can scatter light, further attenuating UV intensity. Because of Rayleigh's scattering law (scattering depends on wavelength to the fourth power!!!), the popular absorbance measurements to determine UV teatability are just window dressing, and not based on thorough science. To make things worse, UV destroys all common chemicals that may have been used prior to the water being irradiated. The biased praise of UV in this article is unwarranted. (PeterH, 2006-09-12)

If you can verify your arguments, why don't you add them to the article? Melchoir 16:09, 12 September 2006 (UTC)

With pleasure, as soon as I have time, but right now I am preparing for a job where the health officer has shut down a UV system because it has contaminated a previously clean hospital piping system, as I predicted, for exactly the reasons outlined above. This and some other similar jobs will keep me busy over the next few weeks, so please bear with me. (PeterH 2006-09-12)

Could PeterH kindly consider completing his commentary as this would prove invaluable guidance on design restrictions and considerations to empower interested readers in avoid the oversights he has outlined? I believe much of what he has highlighted can be mitigated through considered integrated systems design once a full understanding of these factors is achieved. If no verification for his assertions is forthcoming, could they be considered as biased opinion?(Tobyvanreenen (talk) 15:57, 13 August 2013 (UTC))

Propaganda Redux:

As the author of this let me state for the record: I wrote this based on an article I read in regards to ultraviolet used to remove allergens from circulating air. I wanted to check the article against Wiki and was surprised there was limited information about it in the Ultraviolet section. I had no agenda and I certainly don't advocate it. Just being bold. Please update the article with any information that corrects my errors. -- PDream

EEPROM times

I changed "10's of seconds" to "under a minute." Originally I was going to just fix the "10's" (http://www.grammarbook.com/punctuation/apostro.asp) but that still sounded awkward.

ChrisKurtz (talk) 06:06, 3 December 2009 (UTC)

Merger proposal

The following discussion is closed. Please do not modify it. Subsequent comments should be made in a new section. A summary of the conclusions reached follows.

The result was merge. -- zazpot (talk) 03:51, 8 August 2011 (UTC)

---

There are two articles with substantially overlapping content. I propose they be merged with this one. zazpot (talk) 22:59, 18 July 2011 (UTC)

For information, since the merge proposal templates will be deleted once the merge is complete, the two articles referred to above are the ones currently present on Wikipedia as Ultraviolet disinfection and UV water disinfection. zazpot (talk) 03:51, 8 August 2011 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

Advantages

This paragraph is a mismash of semi-related ideas. UV have nothing to do with making water hard. The boiling does not have to be done on a biomass stove. It is not clear what is meant by chlorine treating "larger organisms." The connection with UV and expensive drill rigs is non-existent. And UV does not make wells "immobile." The advantages section does not really give the advantages of UV. KudzuVine (talk) 13:39, 29 February 2012 (UTC)

"Bandwith" of the 254nm line

This line is a chemical property of the mercury plasma and does not shift or widen with regard to power fluctuations. Article was updated accordingly. — Preceding unsigned comment added by 24.96.249.3 (talk) 20:55, 10 August 2012 (UTC)

Please Add

I wish this article said why reflective linings has the greatest positive effect on the SODIS method. I had figured out that by applying it onto the SODIS method, and testing my water samples. I'm still having trouble finding the answer to my question. — Preceding unsigned comment added by 24.225.121.218 (talk) 21:44, 14 December 2013 (UTC)

reply

I agree with PeterH, this is propaganda. The author just used scientific words. 24.225.121.218 (talk) 16:39, 15 December 2013 (UTC)g

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Potential source

• Chatterley, Christie; Linden, Karl (2010-09-01). "Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection". Journal of Water and Health. 8 (3): 479–486. doi:10.2166/wh.2010.124. ISSN 1477-8920.

It's a bit old. Note, "Although research of this technology is still in its infancy, improvements to UV-LEDs are expected to occur rapidly following visible LED source trajectories, resulting in a high efficiency, low input power product." and "Limited research has been conducted on the effective- ness of UV-LEDs for water disinfection" and "Combining projected improvements to power output, lifetime, and cost per mW, results in UV-LEDs being a feasible option and an improvement over LP systems around the year 2013 ( Table 2 )."

Do we have sources showing these projections have been met? --Ronz (talk) 15:29, 15 August 2016 (UTC)

UV irradiation can remove estrogenicity from a water supply?

UV irradiation can remove estrogenicity from a water supply; such estrogenicity may be gained from exposure to EE2, which is overwhelmingly the most common type of synthetic, estrogen used in the contraceptive pill; a woman who takes the contraceptive pill, may excrete EE2 in her urine or feces. According to Zhang, 'Results showed that more than 95% of the estrogenicity was removed after 40 min irradiation and that the parent compound EE2 was mainly responsible for the observed estrogenicity.

This paragraph was initially removed because the source is primary and not relevant to water supplies. Those concerns have not been addressed.

Given the publisher, I'd like some evidence that the source is reliable as well. --Ronz (talk) 19:58, 14 July 2017 (UTC)

• This is kind of misleading. What municipal water supplies actually irradiate their entire water supply for 40 minutes? I don't doubt that in theory, it works, and in relatively small batches, it is effective, but putting it in a section that deals with entire supplies (ie: at least hundreds of thousands or millions of gallons per day), and not just quantities for lab testing, is WP:UNDUE and misleading. If it is included (and I'm not against inclusion if done right), it needs to be qualified better and not framed by paragraphs that talk about entire supplies. This sounds like a small scale theory, not anything that any water supply would use any time soon. Dennis Brown - 2¢ 18:15, 20 July 2017 (UTC)

@Dennis Brown:The paragraph Ronz quoted above was actually changed on 21:41, 11 May 2017‎, by way of response to a comment from another editor who raised similar concerns to yourself. Apparently, Ronz has chosen to ignore the newer version and restate the older version. For what reason I do not know. The newer, edited version was stated in the 'Advantages' section and read:

UV irradiation can remove estrogenicity from water; such estrogenicity may be gained from exposure to EE2, which is overwhelmingly the most common type of synthetic, estrogen used in the contraceptive pill; a woman who takes the contraceptive pill, may excrete EE2 in her urine or feces. In regard to the ability of UV irradiation to remove estrogenicity from an aqueous solution, Zhang states, 'Results showed that more than 95% of the estrogenicity was removed after 40 min irradiation and that the parent compound EE2 was mainly responsible for the observed estrogenicity.<ref>

• • Still, that isn't practical for a "water supply". I'm not sure it needs to be in there at all, and in fact, would say it is misleading. No water supply irradiates for 40 minutes. That was and still is my point. Dennis Brown - 2¢ 17:33, 31 July 2017 (UTC)

@Dennis Brown:I am not applying the statement to a water supply. Do you mean that the 'Strengths' and 'Weaknesses' sections are only for water supplies and not for other uses (boiling is also discussed there)? If that is the case, then perhaps a solution may be putting it in a different section.RickyBennison (talk) 15:20, 1 August 2017 (UTC)

It was right under a paragraph discussing water supplies so it was implied that removal is an option for water supplies. It is not. I think before you put it in at all, I think you first need to explain why it is helpful in an article that covers "Ultraviolet germicidal irradiation" (and is in fact named that), then we can talk where it would go. Estrogen is not a germ, or any other kind of living organism. I'm not convinced it belongs anywhere in this article, although I'm open to hearing why it does belong. I think that is why you keep getting reverted. Again, I really am open to hearing, but at first glance, it appears to be well out of scope for this article, no matter where you put it. Dennis Brown - 2¢ 15:31, 1 August 2017 (UTC)

I don't see a solution without finding some non-primary sources that put this type of research into context which we can then follow. --Ronz (talk) 15:47, 1 August 2017 (UTC)

• I agree that a non-primary source is needed, but even then, why is this important in an article about "germicidal irradiation"? That still doesn't fix the scope issues. Dennis Brown - 2¢ 18:37, 1 August 2017 (UTC)

I agree. The new source would have to establish the link between the topic of this article and the topic of the research. --Ronz (talk) 19:23, 1 August 2017 (UTC)

Hi, sorry for late reply. I acknowledge the scope issues. An argument for including it in this article may be that the removal of EE2 constitutes the removal of an environmental contaminant- and that this removal and disinfection may both be achieved as part of the same overall process which utilises UV irradiation i.e. one process involving UV irradiation both cleans environmental contaminants and disinfects. I am by no means an expert but I think some AOP processes are an example of this. So to add the previous to this article, in more general terms which are non-specific to EE2 (because I have not seen any direct references to AOP and EE2 yet), perhaps a short section along the lines of 'UV germicidal irradiation is sometimes achieved via AOPs, some of which are also used to clean environmental contaminants.' Perhaps the section could be called 'Usage of UV irradiation technology in other processes to both disinfect and clean environmental contaminants/perform other functions.' I am by no means insisting on this, but I thought it was worth putting forward as an idea.RickyBennison (talk) 16:55, 14 August 2017 (UTC)

References

Talk:Coronavirus_disease_2019/Archive_3#some stuff about UV rays to disinfect

I'm thinking of putting stuff like this in the article. DMBFFF (talk) 19:59, 29 March 2020 (UTC)

"far-UVC" light

Can mention of "far-UVC" light, which is currently being used to kill germs in air, be added to this article? 173.88.246.138 (talk) 22:03, 16 August 2021 (UTC)

I don't think far-UVC is a commonly used term. AFAIK pathogens are as well killed by UV exposure whether in air or on a surface, most efficiently by wavelengths in the 250nm range (which is not "far" in the UVC band) which notably includes the 254nm mercury line. There already is a section on air disinfection. Interferometrist (talk) 19:41, 18 August 2021 (UTC)

Reposting my reply to "222 nm UV light" here.

Noting my support to make far-UVC (200-235nm) a separate page. The last several years has seen a lot of research on this spectral band for air cleaning including on safety (recent review), efficacy (another review), and source development.

The safety effects of far-UVC are distinct enough from longer UV-C wavelengths that they allow for disinfection from ceiling mounted lamps that expose the whole room, as opposed to upper-room systems that typically use a peak of 254 nm. There are now several companies marketing far-UVC products.

Theeoliver (talk) 20:14, 12 January 2024 (UTC)

Upper room germicidal irradiation, scientific infighting on US CDC?

As of 2020-2021, there appears to be an internal war going on in the scientific community about how communicable infectious aerosols work:

• Does coughed and sneezed infectious mucous immediately fall to the ground?
• Or does it float through the air for many meters, stay suspended in the air for minutes to hours, and rise and fall in slow air convection currents?

It appears the latter is the more correct interpretation. As such the 2 meter / 6 foot social distancing recommended all throughout the 2020-2021 coronavirus pandemic is effectively useless and should be withdrawn as guidance, because it is mostly pointless except for not having large coughed or sneezed droplets of mucous directly land on you.

There is more discussion about this in a long-form article in Wired magazine, The 60-Year-Old Scientific Screwup That Helped Covid Kill: All pandemic long, scientists brawled over how the virus spreads. Droplets! No, aerosols! At the heart of the fight was a teensy error with huge consequences. 05-13-2021

It appears the fight over this is still ongoing. Although previously the US Centers for Disease Control was promoting upper room irradiation as a solution for fighting coronavirus, they have now withdrawn it with a tersely worded statement that it "may not reflect current guidance" but with no explanation as to why, or any way to get more information on why this change has happened.

CDC information page on Upper Room Germicidal Irradiation: https://www.cdc.gov/coronavirus/2019-ncov/community/ventilation/uvgi.html

In April 2021 this page was changed with a yellow box at the very top:

ARCHIVED WEBPAGE: This web page is available for historical purposes. CDC is no longer updating this web page and it may not reflect CDC's current COVID-19 guidance. For the latest information, visit CDC's COVID-19 home page.

My attempts to get further information about this change have been met with absolute silence from the CDC and the "National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases" cited at the bottom of that information page.

They don't want to talk about it, and I expect it is a huge hazardous hot potato topic for them because an important area of technology that could be used to fight the pandemic is now being quietly suppressed for political infighting reasons.

After all, if coughed and sneezed infectious particles DO immediately fall to the ground within 6 feet / 2 meters of the infected person as the CDC has been claiming all along, what good is an overhead germicidal death ray suspended about a meter about people's heads going to do?

It appears to me that in the USA and around the planet, we should be installing upper room UVGI everywhere. There should be billion-dollar government grant programs to get it into every school and indoor public commercial space.

It is very frustrating to see the technology now being quietly sidelined by the CDC and its representatives, for nonspecific undefined reasons that no one will step up and talk about.

-- Dale Mahalko, Gilman, WI USA DMahalko (talk) 04:40, 17 December 2021 (UTC)

You wrote, "After all, if coughed and sneezed infectious particles DO immediately fall to the ground within 6 feet / 2 meters of the infected person as the CDC has been claiming all along, what good is an overhead germicidal death ray suspended about a meter about people's heads going to do?" I don't know whether you really hoped for an answer, but here goes anyway.

UV light sources a meter or so above people's heads (not sure why you call it a "death ray") would, if the contamination did not float in the air, still be useful, I would have thought, because the UV light would kill the germs on the floor, the tables, people's hands, door handles, mobile phones, and every other surface that faced upwards a reasonable amount of the time.

I created a new section on this talk page just now about 222 nm UV which may or may not interest you, before seeing your post. Polar Apposite (talk) 18:37, 21 January 2023 (UTC)

You misunderstand how this technology works. There is a series of planar metal plates that are flat black in front of the light source with a spacing of approximately 5mm between the plates, and the light path between the plates is approximately 10 to 20 cm long.

This forces the light to be restricted to a flat horizontal beam that shines across the upper airspace of the room with very little dispersion.

Looking up from the ground it should not be possible for occupants to see the light source, so it is not a potential UV hazard for the eyes or skin.

The narrow beam dispersion allows the UV intensity to be very high so that it mutates the DNA in suspended aerosol germs several meters from the light source, but without being a hazard to the people in the room.

This is why I referred to it as a death ray. It is for the microorganisms that pass through the beam.

There may be some hazard for people who must stand on a ladder in the path of the overhead beam. In this situation, it’s probably best to turn these UV sources off while work is being performed. — DMahalko (talk) 10:35, 23 December 2024 (UTC)

222 nm UV light

Shouldn't there be more in the article about the claimed safety and efficacy of 222 nanometer/nanometre UV light, whether confirming or debunking it? I would have thought that there would be at least a section on this, if not a main article, given the importance of this breakthrough, if it is genuine. If it's not genuine, it's important to debunk the claim, and if a bit of both, to clarify the issues, I would have thought. https://www.nature.com/articles/s41598-020-67211-2 Polar Apposite (talk) 18:27, 21 January 2023 (UTC)

The CDC says the range of UV-C is 100-280 nm, so it's not as exact as a single frequency / wavelength.

https://www.who.int/news-room/questions-and-answers/item/radiation-ultraviolet-(uv)

UGVI direct exposure beams are mounted on walls above people's heads, inside a beam collimator frame that removes sideways light rays that could deflect down towards the occupants of the room. The collimator is very simple, just matte black metal plates about 5-10cm long and accurately spaced about 5-10mm apart for a row of LED UV-C emitters.

For a gas-tube discharge lamp (looks like a clear fluorescent tube), a stack of many parallel collimator plates are used since the light is emitted across a large surface area of the discharge tube glass envelope.

In general it appears UV-C is cumulatively harmful over extremely long periods of time, but brief periods of exposure are not harmful. People might very briefly be exposed by holding their hands over their heads, or standing on a ladder.

I don't think there is any requirement for it, but the collimator frame should likely have a visible light source next to the UV-C emitter, such as a red LED in each plate gap, so that if people accidentally look in the direction of the emission source while their vision is in line with the collimator, this would serve as a warning that they should look away to prevent the UV-C from irritating their corneas.

I would expect that as with any UV-C source there may be gradual bleaching out of paint, varnish, plastics, or decorations around the perimeter of a room that are at the same height as the collimated beam that is being projected across the room onto the walls.

-- DMahalko (talk) 03:09, 24 April 2023 (UTC)

None of what you wrote in your reply to my comment addresses the point I was making. Please read it again, and reply with a relevant comment. Polar Apposite (talk) 01:35, 21 May 2023 (UTC)

Hi all!

Let me start by saying that I'm a complete newby to editing Wikipedia, so apologies for the newby mistakes that will inevitably make at some point.

I just finished a several months long investigation into far-UVC and other air cleaning UVGI applications for a research review paper. As a result, I think I'm fairly up to date on the state of the field and the science and I'd like to contribute to this page.

In particular, I'd like to expand the section on air cleaning and include more discussion about far-UVC. Also, in the safety section, I'd like to add a bit more nuance regarding the effects of different UV-C wavelengths and discuss the exposure limit standards from both the American Conference of Governmental Industrial Hygienists (which revised limits in 2022) and International Commission on Non-Ionizing Radiation Protection (ICNIRP). The ACGIH limits cited are pre-2022 limits.

Do such changes/additions sound appropriate? I'll begin drafting more concrete text in the next week or so. Theeoliver (talk) 17:06, 19 June 2023 (UTC)

Welcome to Wikipedia. What you proposed sounds great. Just remember to use citations and use the correctly, by which I mean that the citation should truly make the point that you are making in the WP article. Also, I'd be grateful if you would say something about 222 nm UV, either confirming it as breakthrough or debunking it. Polar Apposite (talk) 21:35, 5 July 2023 (UTC)

Noting my support to make far-UVC (200-235nm) a separate page. The last several years has seen a lot of research on this spectral band for air cleaning including on safety (recent review), efficacy (another review), and source development.

The safety effects of far-UVC are distinct enough from longer UV-C wavelengths that they allow for disinfection from ceiling mounted lamps that expose the whole room, as opposed to upper-room systems that typically use a peak of 254 nm. There are now several companies marketing far-UVC products. Theeoliver (talk) 20:11, 12 January 2024 (UTC)

Sounds good to me. Polar Apposite (talk) 20:47, 12 January 2024 (UTC)

I also think that far-UVC could warrant its own page. I'm beginning to work on a draft. RDX300 (talk) 21:39, 19 July 2024 (UTC)

Draft here Draft:Far-UVC RDX300 (talk) 13:42, 22 July 2024 (UTC)

Could someone with relevant specialist expertise please comment on this draft. Polar Apposite (talk) 18:57, 24 July 2024 (UTC)

Im meeting with two far-uvc experts tomorrow and will be making updates RDX300 (talk) 19:23, 24 July 2024 (UTC)

After this I will submit draft for formal review process RDX300 (talk) 19:23, 24 July 2024 (UTC)

I reviewed the draft and made some revisions to the parts concerning safety. The rest of the draft conforms with my understanding of far-UVC. Theeoliver (talk) 15:14, 25 July 2024 (UTC)

Edits look great thank you so much for the contribution!! RDX300 (talk) 15:41, 25 July 2024 (UTC)

UVGI hand sanitizer.

https://uv-can.com/products/far-uv-222nm-safe-hand-sanitizer-station is an interesting product. I wonder whether it works as advertized and whether the idea is a sound one. If 222 nm UV really is harmless to the hands and eyes, why not? Polar Apposite (talk) 19:04, 21 January 2023 (UTC)

Germination is not germicide.

I deleted a block of text that was about using UV for germination. Maybe I undid some vandalism, I don't know. Certainly it didn't belong at all, and this should have been obvious. The heading was "Background" which seemed a bit weird. Polar Apposite (talk) 21:52, 21 January 2023 (UTC)