F.A.Q. — My Research on FAR-UVC lights

I am a layperson interested in utilizing FAR-UVC lights to keep myself and others safer during in-person interactions.

FAR-UVC is a potentially revolutionary technology that can deactivate Covid and other pathogens. That said, there are also a lot of untried vendors moving into this space and it’s a bit like the Wild West right now. Trying to separate the wheat from the chaff is a time- and energy-intensive task, especially for someone such as myself who is already disabled.

Let us just acknowledge that the government should be investigating this, promoting this, and setting up safety guidelines….not some mostly-bedbound person who just wants to go to the dentist again.

But that’s not the world we live in right now. Until business interests decide that keeping regular people uninfected is good actually, FAR-UVC will remain the province of powerful people like Covid Response Czar Dr. Ashish Jha, who uses FAR-UVC to keep himself safe, while simultaneously doing absolutely nothing to advocate getting these lights into classrooms, healthcare facilities, or public transit.

Disinfection For Me; Reinfection For Thee

(photo linked from https://www.wsws.org/en/articles/2023/01/14/teda-j14.html , showing “White House COVID Response Coordinator Dr. Ashish Jha speaking at an event with multiple UV lamps disinfecting the air. [Photo: Joey Fox/@joeyfox85 via Twitter]”)

On To The Science

First, in an effort not to duplicate work, I’m going to post this fine presentation written by another layperson, who has some background in the math required to make sense of this stuff. He articulates why he thinks Sterilray is a better choice than its competitors such as Krypton.

I am now ambivalent about the Sterilray, mostly because of the issue that they have an unfiltered product. When I have some time I will link to online conversations I have had about that. But for now I will keep this document here as a record of the research I did do, which might help others.

Again, if I have time / energy I will update more, but for now feel free to search for @realsexycyborg on twitter to see her conversations about FAR-UVC and her comments on the product from Sterilray.

I spoke at length to a rep from the Krypton company and from Sterilray, and the impression I got was that Krypton had prettier products and better marketing, while Sterilray was a more powerful product, and the company was run by engineers who were stronger on the science. Engineers aren’t great at marketing though, as was evidenced by the fact that they casually mentioned that the New England Patriots are using their devices — any normal company would lead with this fact and plaster pictures of the Patriots all over their homepage.

I’ve asked the CEO a bunch of questions, so I’ll post a lightly edited version of all those email and phone exchanges here. When I summarize the phone calls it’s to the best of my recollection.

Some white papers on the Sterilray website.

Q: Does it do anything against dust mites? other pests? Bedbugs?

A: The short answer is yes, but it depends on the ease of getting a line of sight on the pest itself.  We have successfully tested eradicating mites in agricultural applications. (I spoke with him on the phone about bedbugs, he said that technically it kills bedbugs within seconds, but since bedbugs hide inside mattresses and within walls it doesn’t really work — the light has to touch the insect for it kill them. But it should work well on dust mites.)

Q: Are there any test kits or other things people can buy or be supplied with that help us test that the device is continuing to operate within safe parameters — I’ve heard of test strips or things like that? Basically something you can do every once in a while to make sure it’s still safe since nobody has a dosimeter in their house. 

A: There are a few mail-in kits for both surface and air sampling, but the easiest method is to use the Intellego UVC dosimeters which are relatively inexpensive and provide you with quick analysis of UVC dosage. https://intellego-technologies.com/uvc-dosimeters

Q: What square footage or cubic footage would be made safe by using one sabre? And does the ACH {air changes / hour} equivalency calculated change based on the total size of the space? {Note I am including his reply unedited, but it is so math-heavy that it is not that useful to a layperson. Scroll down to find more layperson-friendly follow up questions}

A: Unfortunately, there is no simple answer to your question.  There are a lot of variables at play.  These include:

                What pathogen are you trying to deactivate?

                What level (ie. Log 3) of deactivation are you trying to achieve?

                Are you trying to disinfect the air, surfaces, or both?

                ACH equivalency is an imperfect metric given the variables above.  However, if used in context with the answers to the questions above it can provide a reasonable estimate as to safety.

With our lamps, range in size from 325 sq. centimeters to 1240 sq. centimeters and have input power from 150W to 1.2kW. we generally will spec 2w/foot as the range and 4w/ft. as the width to get a log 3 reduction of aerosolized Covid or Influenza in one second or less.  Calculating ACH is relatively simple from the cubic volume.  Generally speaking, our correctly sized configurations will range from a few hundred ACH to a few thousand ACH.  That includes the Sabre, when used for air disinfection of viruses and bacteria.

Q: How quickly will the sabre work in a dentist’s office so that I can feel fairly safe taking off my mask and getting dental work done? Do I need to run it for some period of time before I start the procedure?

A: The Sabre will deactivate the aerosolized Covid virus almost instantly…therefore no advance use of the lamp is required.

Q: If a person is immune compromised, but they would like to be able to eat Thanksgiving with their family again, is there a size of room + sabre configuration that would make that pretty safe to do indoors?

A: As long as there is line of site to the immune compromise they will be protected from any airborne viruses.  Certainly, even a very large dining room would be well within the coverage area.

Q: We’ve all heard stories of people getting Covid even outdoors, like at an outdoor wedding. If somebody were to eat outdoors *and* run a sabre, would they be pretty protected from getting covid?

A: The answer is absolutely yes.  The technology works equally well outdoors as it does indoors.  Wind and climate do not impact the efficacy.

Q: Let’s say an immune-compromised teacher is forced to teach in person. She is wearing a mask but her students are not. Would she be safe to teach if she were using a sabre? What size classroom, max footage, would be made safe by ONE sabre? 

A: One Sabre is adequate to protect an entire classroom but the issues arises regarding “shadowing”. That is why we typically recommend two fixtures for a classroom, one on end wall and one on an adjacent 90 degree wall.  However, if the intention is simply to protect the teacher, on Sabre should do the trick assuming the teacher remains in the line of sight.

Q: What’s the ideal distance a person should be from the lamp for max protection / min corneal irritation?

A: Corneal irritation is not the issue, it is more the evaporation of the oils around the eye that cause the irritation.  Five feet would be the safe distance to avoid such irritation.

Q: Is this considered Durable Medical Equipment? Could I get reimbursed by my health insurance?

A: While there are HCPCS codes for ultraviolet light therapy systems, I am not aware of any reimbursement codes for general air and surface disinfection.  I do believe it is only a matter of time however as more data becomes available regarding using Far UV to reduce Healthcare acquired Infections and surgical site infections.  As we begin to roll out our FDA approved medical devices we will do so in conjunction with getting the codes available.

Q: Would the sabre work in a small solo train compartment? A roommette on Amtrak, for example, is 3’6’ X 6’6 , while a bedroom on Amtrak is 6’6” x 7’6”. 
    Would this give enough distance to sit safely with a Sabre for a full day trip? Or would it be too close for eye and skin safety? 

A: I don’t believe you would need to run the Sabre for more than a minute or two every hour to keep the cabin disinfected.  In that case you don’t have to worry about exposure time.  If you can maintain a five foot eye distance from the Sabre then you don’t have to worry about running it intermittently.  If you are too close, it won’t harm your eyes but it will make them tear up.

Q: So 5 foot distance minimum if you are running it continuously? If closer than 5 feet than only run it


A: Generally, I think that is a good rule of thumb.  If you are closer than five feet, your eyes may dry up and then begin

to tear up.

Q: What about ozone if you run it in a small room?

A: No ozone worries…we are well under the NIOSH and CARB limits.  You will get some smell (not Ozone) initially due to the heat of the lamp creating a non-harmful VOC from the plastic of the Sabre.  That generally goes away after a few uses.

Q: This pre-print article seems to say that 222nm light can pose a threat to DNA…?

A: We are very familiar with this paper and actually think that their studies further validate the efficacy of 222 for breaking cellular bonds. There are a couple of major problems with this paper however. The first is that it is a in vitro study, not a live or even three-dimensional cellular study. They do however acknowledge this fact in their discussion. They also acknowledge that the outer layer of the skin…the dead skin layer, protects humans from any of the DNA damage their study examines. This is because the dead skin layer…the stratum corneum, completely absorbs the 222 wavelength. Unfortunately, they also claim there are a lack of studies that are longitudinal in nature and validate the safety. That statement is patently false…they just have not done their homework.