July 28, 2024 M Pang, Engineer and Co-Founder of OpenAeros, walks us through the nuances of Far-UV use. They'll discuss topics like placement, efficacy, brand comparison, and use scenarios. They have also generously offered to take questions after the presentation.
Recording on youtube Practical FarUVC with M Pang, OpenAeros Co-founder
https://youtu.be/vUweLvJS9IA?si=LtqqTIx0Ekq0ynnO
Super excited to have M Pang, it's been a long time in the planning. They are expert in filtration, ventilation, UV and other things, many know them in our community, co-founder of Open Aeros, and is not affiliated with any companies selling UV devices, its community work.
Slides Open Aeros The OSluv Project Practical FarUVC
Small open source aerosol company in St, Paul with Aaron Collins the Mask Nerd
Sensors used for fit testing and particle measures
Trying to make devices that are more affordable
Osluv Project nonprofit for clean air focused on far UV
Chemical engineer training and career
Practical FarUVC, there is a lot of info floating around, trying to distill it down to the important takeaways and to answer your questions.
Critical thinking strongly strongly encouraged, this is a very new field, every week or two new papers pop up and challenge currently herd assumptions
I am likely very wrong about many things I’m about to say because the science is so new and still evolving. And there nuances and details that matter in a lot of different individual situations.
Presenting the science as I understand it today, but its changing all the time and evolving.
Just because this stuff is deeply technical and there is all sorts of minutia I’m going to fly through these 6 slides, will pause for clarification, the main portion of presentation will be a community Q&A
Bring Intro into FARUVC
SKin & Eye Safety
Indoor Air Quality Considerations
Efficacy and Pathogen Inactivation
Figures of Merit and Buying Advice
Deployment Do’s and Don’ts
Far UV of UVC 200 to up to 400 nanometers.
UVC 200 to 280 is pathogen inactivation
254 upper room UV been around since the 40s, well established well understood tech,
New cool tech in 200 to 235 nn range
254 can affect skin & eyes so considered more dangers, have to be careful about dosage/expsoures
The 200-235 is safer can be used in teh whole room, not just out of sight
222 nm most common wavelength of new
What does GUV stand for? Germicidal UV - the EPA doesn’t like it, eventually the government will come up with their own term, so its being used less.
Safety stuff
Until June this year, convention 222 nm Krypton chloride source, proteins in skin & tear layer of eyes would absorb all far UVC protons, so none of the light could reach living cells, so have built in sunblock to this wavelength of light, but bacteria and viruses do not have built in sunblock and are inactivated very strongly by these wavelengths of light.
There is a wavelength depedant safety curve.
240-300 nm are more dangerous, shorter especially at 222 considered safer, longer exposure is allowed.
Unfortunately a lot of theory went out of the window, in June 2024, Columbia University team found that the tear layer in eyes doesn’t really do anything protective against UV light, and a team in Germany is finding something funny happening chemically in the skin with UV light exposures, so academics are raising new concerns about safety of these lights - but its brand new research so we don’t really know where the exposure limits need to be reset - they probably do need to be lowered, but we don’t know by how much.
However having said that, the damage and the chemistry being observed is at very high doses and happening in very low amounts, so we think that probably far UV as being used by our community is largely safe, but there is a lot of uncertainty and new development.
A lot of the scientits working on this would personally consider it safe, but its not yet settled.
The research that has been done on safety so far is really encouraging, this damage is only seen at extremely high doses and there have been a lot of studies that show this is generally well tolerated.
There are a few studies coming up raising questions about skin & eye stuff, but generally the consensus is that the tech is safe, with caveat that this is filtered with only 200 to 222 light, not the unfiltered that goes up to 250 frequestinc
Q are the thresholds different for kids or pets? We don’t know, more studies have to be done, not much funding for this as pandemic funds dry up - people think that they are ok, but we don’t actually know if its different for different pet species, infants, ect.
Kara We love scientists that will say ‘we don’t know’ because that is the answer sometimes.
Different droplet sizes - we also don’t know for sure. Consensus is that larger droplets have reduced UV penetration, but we don’t’ really know for sure - its thought to have some effect, but within 1 micron or so size, respiratory particle size, there is good efficacy, but we don’t know for sure, and there is new modeling coming out that address this some.
Is there a way to check that your lamp is filtering correctly? Answered later
1 year continuos exposure hairliess albino mcie and human volunteers of 222 nv with no changes in skin or eyes
208 krypton bromide lamp, difficult to build
222 is easier engineering, not necessarily the best for efficacy for safety -
230 might be best for efficacy, but more difficult to build.
Probably not damage to skin microbiome, because that is refreshes continually throughout the day.
Not ionizing radiation, peptide bonds but german group finding secondary emission effects, 222 coming in creating reactive species, creating something else hours or minutes alter (very high doses, new science, not published yet)
High dose substantially in excess of ACIH limits.
243 & below generates some amounts of ozone, which can reated with VOC to create undesired species including new partimate matter.
Ozones level sin sealed chambers for tests much higher levels than realistic conditions - portable air cleaners, catalytic or activated carbon scrubbers can remediate this.
Aaron Collins did find ozone in his hotel room, that had a lot of perfume in hotel, little ventilation, using a UV light he found particulate matter and undesirable species - primarily a problem with low ventilation and high VOC - can be fixed with ventilation and/or air filters - its a small effect that you can mitigate - if you are using 222 light you should be using a air filter anyway - the hotel room problem went away as soon as HVAC was turned on.
Efficacy - ability to eliminate pathos
Various different pathogens, far UV is pretty good at inactivating, in small scale in labs as large scale chambers
We don’t know how much it inactivates (K value) larger k favlue better inactivation at lower dose, there are variances in k from 0.1 to 100, this is a log function, so very different values, we are actively working on setting experiments to determine this, we don’t know why there is so much variance.
My non profive the Osluv project is working on this.
In a small chamber k on order of 10, in big room its 20 or 100, and that is a big disagreement in the data indicating that there is something else going on that we don’t understand yet.
Efficacy - does it inactive viruses - yes.
Effectivness is real world settings of efficacy - its difficult to get data
Some real work showed 20% reduction of sick days, but tehre is no gold standard study to see how effective real world use is - there are some small scale studies, but not a good amount of data on exactly how effective the technology is.
Data for liquid & air, those data disagree with each other, I’m mostly talking about air because covid is primarily airborne - even in the same media there are differences in how experiments are performed.
30% improvement is great, why isnt’ it even better? We don’t know. It could be to make this happen right, you need to cover every single space, a 1941 study showed good results reducing measles epidemic, then a followup study failed - kids in first study walked to school, in followup study they rode buses together.
What matters when choosing a lamp?
Critical
output power, how much UV 200 nm - 230nm is it making, typically in milliwatts
Weighted spectral output -is that safe - ACGIH or ICNIRP standards
Lifespan of UV emission - how long will it last? 10 hours, 100, 1000? Be very skeptial of warranty claims - a lot will continue to emit visible light long after they stopped emitting UV light
Good to Have
Shape of emitted light - broad is better than narrow beam
support/repair/customer service
3rd party validation, certification, regulatory compliance
Meh dont’ care about
Electrical input power 3W, 12W, 150W not helpful, typical in watts, doesn’t matter, input power and output Uv are VERY UNRELATED and I don’t care what the wattage is, onthe output.
Raw irradiance/unweighted spectrum numbers
Protective bubble size, square foot - because affected by space and density where its being used.
How to get info from the manufacturers - have to be very insistent and it can be very difficult to get this accurate information, its yoru right as a customer
My nonprofit and other nonprofits are testing devices and publishing information about them.
There is no generalization you can make for long long a lamp is a good for - some will die in a matter of weeks, some are good for many years, it varies greatly by manufacture and specific lamps.
Is there a certification or validation for consumers to relying on? Only for safety UL8802 is good safety certification, but nothing about output power/efficacy.
Graph of Steriray Saber, provided to ISO certified lab by sterilray, half paid by steriray, half paid by community.
Input 98.48 wats
Output 480.4 milit Watts
0.51% efficiency
The lamp shapes the light as it comes, you want to cover room entirely, so consider the shape of the light coming out.
Relative emission strength unfiltered KrCl lamp main peak at 222, but smaller pea at 258
Unfiltered Eye Hazard (weighted graph), the small 258 peak makes large eye hazard peak.
Filtering the light can substantially reduce amount of unsafe frequencies
Do optial filters fail over time? Generally no, but you can break them. Some might degrade, but pretty hardy, silicon dioxide, you should be gentle with them and not crack them or use sandpaper cleaning.
Graph & chart comparing unfiltered versus filtered ANSI/IES eye limit more than 100% is not good, higher is worse.
Unfiltered not unsafe, to use it safety, you need to have it farther away from you than a filtered lamp, and use for shorter periods of time.
Commercial off the shelf lamp 200 to 230 output, graph running it for hundreds of hours, after 520 hours dropped to 70% of initial output, after L70 (70% of output) call the lamp spent . The visible output does not change, but the pathogen inactivating parts of the light decreases with use - manufacturers might claim they last longer than the L70 really does.
If you have a very expensive measuring device you can collect this kind of data, or at home you buy these dots that change color from exposure to UV light and look at this chart to determine approximately that your lamp is still ok - these are cheap and affordable tests UVC Dositimers pearllamps.com less than $20, only need to buy 1 pack, there are several of these sticks in a pack
Far UV /UVC sort of the same thing
Safety limits set by some experiments, some consider them to be very conservative. The larger of the dose you take, the more chance of some kind of damage - but even when people have exposed themselves to ridiculous amounts, it seems to be more of a temporary sunburn or scratchy eyes not long term damage, but there isn’t clear data for sure about this.
Talking to researches who did the skin & eye research, they personally tend to think there is not long term issues (question about cancer), but the science is too new, more research needs to be done.
Shape of light images, broad beam, or a diffuser to broaden out the lamp, you want pathogens inactivated before they are breathed in.
Important to independent 3rd party data.
My non profit buys or are given lamps and we measure them on our setup and make sure they are performing accurately to their claims. Not a single lamp has performed accurately to all claims by the manufacturer. I don’t think its malicious - its a very new technology, there is a lot going on that even the manufacturers don’t know about their products.
Reflectors of visible light does not necessarily reflect UV, but some do. Some reflect far UV but not visible light.
Very far away from federal regulation - california nearly banned them all, but we talked them out of it - we are very far away from any kind of federal regulation.
Glasses will stop pretty much all UV - in general eyes take a very small dose because not looking directly at the lamp, glasses do stop almost all of the light
Far Uv for fomite/surface? It has been shown to inactivate pathogens on surfaces - remind me after talk, college Vivian has an excellent spreadsheet, list of all the pathogens and K values, remind me to link.
Yes, it will help for fomite transmission, but can take minutes or hours especially from far away, there are UV devices you hold close to surfaces for disinfecting.
Installation
There are a lot of minutia - you want to maximie the volume of air that is covered by the light, maximize the path length - not 3 feet facing a wall - you want to travel as far as possible in the room, pictures of several placements, on ceilings pointed down & at angle, high on shelves, pointed down at angle. Also very helpful to put portable air cleaner. I argue before you spend a single cent on UV, put in a portable air cleaner, it will break up short range transmission and help the UV be more effective.
Short Ranger Transmission is still a problem!
UV really struggles with short range transmission
3 USHIO Ba, same as 1 Sterilray sabre, directly above a table, about 10 or 20 times more than you would have a in a room, nuke the heck out of the room here - if you have people sitting at ends of the table, it only takes about 1 second for exhale to go from one person to inhaled by another person - only 42% inactivation in 1 second.
Using Kwon 2020 restaurant infection from airflow -
In general I don’t klike instally UV as protective death bubble in front of you - it is not enough for short range transmission, I’d want it high above, at edges of table, cover as much of the space - its better for long range transmission than short range transmission.
26 papers, remind me to add them to the community stuff, and I’ll update you as new stuff comes out.
Keep in mind, you want as much as possible to minimize short transmission - a portable air cleaner would mix stir the air & give the UV longer time to act, its also important to note that we need to think about the safety of close range lamp, you really don’t want to be like 2 or 3 feet away form this thing, you might take a dose, get scratchy eyes - as a professional I cannot advice you to violate the safety limits
Finally what happens if we put all the interventions that we know about together and what is the priority level?
Chart just adding PCR testing even without masks and long contact, reduces transmission - its removing the pathogens.
In my opinion
Air filters, corsi rosenthal boxes, other portable air cleaners I didn’t recognize, also HEPA, but I don’t choose HEPA first. For ventilation all have to consider PM2.5 and depends on outside conditions - you don’t want to bring in wildfire smoke
Case Study Classroom 13 & 20 & 9fit high
2 BioAbundance B2 difficult
No safety issues,
Fine for skin & eyes
Efficacy depends on which pathogen - charge of 10 pathogens there is a lot of uncertaingin in the data.
Getting good 10 or 20 ACH from the UV, but it really depends on which pathogen, and whose data you choose to believe
0.3 ACH to 30 ACH Kvalve 0.2 to 21 - circumstances of the study matters.
I think its around 10 or 20 for covid, other pathogens are going to be different.
The Price Performance Problem
Portable air cleaner 95 cents per cfm CARD
Diffused UF Lamp @$2.84 cfm CADR
Portabiel air cleaners are pathogen agnostic - works the same for all
UV lamp pathogens specific - good for covid, not necessarily for TB
Pros and cons to air cleaners & UV, I personally would FIRST put air cleaner in - and with additional budge or additional layer of protection , THEN put UV lamp in.
Layering defenses is important.
M Pang has agreed to join a still coviding far UV facebook group, will put files in this new group
Still Coviding, Enlightening UV Discussion
https://www.facebook.com/groups/850963926907976
Community built DIY 3D printed lamp for UV bulbs, want to put files for this on the internet, its near and dear to my heart to work for bipoc community , I come from bipoc community in malaysia, i’m pushing aggressively for this - if there is community interest I would love to be involved.
HVAC systems is moving really fast, so you have to put a shitload of UV light in there to effective inactivate, but it's very expensive, you have to change the bulbs - yes it does work but its expensive and a pain the ass, it's probably better to UV in a room where air if moving more lowly.
Personal air cleaners, Wynd and others
Aaron has tested a lot of personal air cleaners
It's possible to create laminar flow of clean air into your face - the problem is to do this well is very difficult and the thing would have to be huge.
The small personal air cleaners are delivering cleaner are air, some tens of percents - less than 1% of protection -I personally would just wear a mask.
We’ve tested a lot of UV devices, we are publishing them slowly, one at a time, there are 5 or 6 we published, more that we’ve tested - some manufacturers have asked to take down our test results of their device - and we don’t want to be mean to them. It's a new industry and I don’t want to hurt anyone’s business, mistakes get made - I will talk to people personally about what I know about different devices.
Inactivate is not binary, is not clean exponential decay L Hadres from Bristol have done very clever studies, levitate pathogens and watch them get emaciated. Complex step function, multiple things happen to inactivate the virus. Yes - we think that once you give it enough of a dose it will be inactive, so multiple passes does help.
IN RV- put up in corner, in most open area, up high let it shine down - what is the maximize amount of volume you can cover, and the longest past of the light - as much volume with the light on it as possible.
B1 is not diffuse B1.5 is diffuse Big event space, long path length, don’t need diffuser, smaller more crowded space you want diffuser - so what you want depends on the room.
Sterilray sent a unit to an independent lab, got spectra, 3 times more safety budget per unit of light compared to ushio b1. Need at least 9 or 10 feet away for sterilray, without a filter
Canada - there are devices available, I believe so, I’ll post links to them after. I know there is a Canadian group working on this.
Showing spread of light from sterilray sabre in response to a question.
What to buy? Depends on price, and other factors:
Some controversy with Nukkit one nukkit 20 milliwatts of UV reasonable job (similar to krypton tabletop) one bio abundance B2 makes 50 milliwatts, ok job, sterilray about 100 milliwatts some issues in our community, return issues, but seem to be ok, provided you have the space to put them far away, lit thinking for hospital or business, have all the certifications, lumkin does ok. I’m not going to be mean about anyone’s product.
Output per unit size is reasonably consistent.
Krypton I think their far UV went out of business - they make reasonable products - if I know a company is struggling I don’t want to give them $2000 because of warranty, but they make good products.
Is there a portable air cleaners you recommend - any CR boxes, or clean air kits, or tempest
Can you put an optical filter on a sterile , about $100 filter, have to get it custom made probably not worth it, just give yourself the 9 or 10 feet and you would be ok. Install so that its not in your eye light, facedown on ceiling, because no one is going to stare at the ceiling for hours, also minimize how long you are looking at it. 3 feet away has 90 minute standard safety limit
Other companies that publish some data - but a lot of them charge $2000 and manufacturers can’t afford to do this more than once - and so when products change it doesn’t always get caught.
We DIY our own lights, (asked what does your office use itself) about $500 assembled
We are actively and aggressive working on ways to get these in lower income communities, we are a small non profit, its Aaron and I in our space time, if you are in a organization for communities that want this, please get in touch with us
Does far UV bounce off interior surfaces - very little, 90% is gone after the first bounce.
Ozone monitor to detect what far UV creates costs $5000 - opening the window is sufficient to deal whatever the UV might add.
Dentist
M pang got a dentist to install filters and masks, and the first appointment. If I couldn't do all of that, time it during covid lulls or after vaccines, put sterilray or whatever up high, the more you can do all the other things the better.
Open Aeros updates?
First UVC bulbs versus sterilray bulbs - both coaxial, not optimized for lifespan.
Ushio makes very long lasting bulbs.
If you can smell sterilray in a room - yes it is ozone, and probably something is arcing - there is a problem, please don’t use it
Because it's been so hard to study airborne disease transmission, there are a lot of estimations and modeling, but there is a chicken & egg problem in science right now ,people are working really hard to figure it out, but not there yet.
Costs are going to floor at $400 or $500 for USHIO emitter,
$4 a milliwatt is where it is right now and i think that is close to floor,
It's not people being greedy, it's all the overhead costs, if you only sell 500 a year, and have 3 engineers on salary working on them, as well as admin - that is why the lamps cost so much, its to stay in business, I think costs will eventually come down as they are sold more.
Question place nukkit facing me on my desk would be helpful? Yes but be careful how close they are to you, it's better to have them facing down on you, and pointing at the most volume of air
If I had a lot of money first I would buy
Superbugs created from UV resistance?
European data about having them in hospitals - you need to expose for hours, but good results killing everything in empty hospital rooms for hours, without creating superbugs.
Lorel, Midea, chinese factory bunch of brands, it's the one if you on clean air star dot com it's the best one, they do good recommendations
Open Aeros have Cepheid PCR machine bought used & repaired, covid cartridges cost $38, can pool test 5 to 10 people, Cepheid genex, have a lab license and paperwork - we are nerds that is why we refurbished, please use pluslife they are nearly as good and we use them a lot personally - can find 30 to 50 copies of sarscovid,plus does a few hundred, quantitative results, really good results catching early infections, catching people at office before they are infectious, so far no spread at all in office
First thing is Open CPC condensation particle counter - can be used to do fit testing, but it is not a fit tester, has bluetooth, wifi, usb, we have been doing fit testing with it, it will only do N99 N100 fit test, so if you are wearing mask with less filtration, it will report artificially low fit factor, its intended as research device, not a fit test - we are working on a fit tester, but its expensive and slow, we entered NIOSH fit test challenge for Open Fit, if we win, it will go a lot faster
Does open aeros and Osluv accept donations, yes we do, Osluv is tax deductible, open aeros is not - Aaron and I don’t believe in pre orders or kickstarter, there will be a page to sell things that we take money the day we ship them.
Work policy - might amounts of UV, over 10 air changes an hour from multiple filters, people test every other day and don’t mask - we are comfortable with every other day because using the PCR picks up 30 copies of SARS2, so exponential growth of virus, we are confident that every other day is sufficient - people have been asymptomatic, come in the morning for a few hours before we test them and send them home, cycle totals 35,40, need to be at 27 to be infectious.
If we have a visitor then everyone masks up.
With pluslife they do have a several thousand dollar unit that tests multiple test cards at once - but they don’t guarantee refund if customs interferes, they do guarantee either refund or replacement for the minidock if customs interfere.
Actively working on open source testing and talking to Leo & Connie at virus.sucks - we have validated plus life, but the virus.sucks guys did a much better job of it.
Lab in Wash U in st. Louis covid breathalyzer, colleagues working on it, just got funded.
DIY have used bulbs from several manufacturers, but I think Ushio are most efficient for cost and long lasting.
All research tools, not direct to consumer or affordable.
Small wearable air samples
Microwave toaster size air sampler $5000
Regular testing is the solution to many of life's problems.
We have colleagues working on breathalyzer instead of swabs just got 8 digits of funding , - hope is there just have to give scientists time to work. - I handled one of the first working prototypes last week.
Do you get pushback about techs working on?
All worked about decreasing in price, but being really nice to us and accommodating but I suspect that is because we are in R&D & might get nasty once we start selling things.
Is metrix saliva good enough for screening testing - response that plus life with a mouth swab is better, I’d be comfortable with mouth only pluslife swabbing (nose also is better, but mouth is sufficient)
Question about schools using grants for precautions.
Air Gradiant - indoor air quality monitor, and clean air kits - and pair them, even you don’t do anything about covid, you help with PM2.5, asthma, wildfire smoke, ect, its very important in my opinion we go to schools have paired air monitors and air cleaners - to help with issues when schools bought hepa filter sand never took the plastic covers off and don’t turn them on.
We do local outreach for pollution reduction, you need both a monitor and a fix like air cleaner.
Sterilray escones are different bulbs than saber, don’t have data - sterilray know nows they can pay $900 to get testing done on each product and I think they should. I would buy the dots and put them around and time it and compare it to what the dose should be, put them where you sit or eat or whatever and do that, make sure they aren’t expires.
No, I would not eat indoors in a restaurant even with a giant ring of UV as my only protection, I would wear a quantitative fit tested mask indoors.
I have to travel for work, I wear elastomeric, aaron wears vlfex, we have a well practiced procedure, tested in the office to measure how much we are inhaling that means its takes over an hour to carefully eat a meal both inhale , break mask seal, pop food in, close mask to chew and exhale and do that again, you are talking about 13 breaths a minute, fit factor of 100, every 8 hours that's about 20 or 30 or breaths, so taking mask off, stuffing food in and putting mask one, taking one full breath does not significantly increase the amount of pathogen you are inhaling - but this is all black magic that aerosol scientists do. 8 hour flight, fit factor of 100, expected leakage means about 8 unfiltered breaths equivalent, so my point is taking 1 full unfiltered breath isn’t much more than expected leakage. All of us wear fit tested N95 masks, and travel a lot and have been ok (but others call survivor bias, but also called that they all probably practiced how to be very fast and safe way to eat while masked).
1 second across the table was a mean - exhales can be 4 times as fast, and sneeze even faster.
40% reduction from UV is great, but it's not the 99% reduction that everyone is pushing.
Illuminate.osluv,org
documents/links to remind M Pang to share in Still Coviding, Enlightening UV Discussion https://www.facebook.com/groups/850963926907976
The slides from today’s presentation.
Canadian UV units/group
Vivian has an excellent spreadsheet, list of all the pathogens and K values