Effect Measure

Masks and UV light

Several readers have pointed me to an online piece on face masks and ultraviolet light as influenza control measures just published in the American Journal of Public Health. Both are presented as a Plan B in the (lkely) event Plan A’s vaccine and sufficient or sensitive antivirals are unavailable. The review by Weiss, Weiss Weiss and Weiss (I know a joke that goes like this, but this isn’t a joke) is measured an informative. First, face masks.

The authors point out that cloth surgical masks protect other people from you, not you from them. They discuss N95 and N100 respirators and provide interesting background on specifications and performance. The confusion as to the size of the infective particle in influenza transmission is reviewed, and the authors suggest that even large droplets may remain suspended for significant periods and travel longer distances than assumed, citing old literature and noting that newer literature is uninformative. The lack of data is startling. Whatever the data, no controlled studies exist on whether respirators can prevent influenza transmission, and serious questions exist on their feasibility in practical situations. They point out that without knowing the minimum infective dose for influenza we cannot know if even 98% aerosol protection is enough. The remaining 2% may be sufficient to infect.

There is also an informative discussion of leakage and fit testing:

Fit testing is time consuming, and in the health care setting, requires a technician. The test typically involves molding the mask until a seal is accomplished. Coffey et al found that most persons cannot be adequately fit tested to commercially available N-95 respirators.

Furthermore, it is uncertain if the utility of fit testing extends to beyond a single use. We could find no measurement of filtering efficacy with removal and immediate reapplication of the respirator, nor were we able to find any data to support the supposition that fit testing in 1 model of mask carries over into other masks of the same make and model. We also were unable to find assessments of efficacy after sustained use. The face is not a static surface; for example, motion of the jaw from swallowing, facial grimacing, or talking likely alters the seal. Even if all of these variables are negligible, there is still the effect of gravity pulling down on the mask. (Weiss et al., AJPH)

On the other hand, they suggest that using a cold cream or vaseline sealant might be a temporary workaround in an emergency, although its effectiveness and durability are unknown. It’s something to keep in mind. Their bottom line is equivocal: masks may be the only game in town and in that case, it’s a game worth playing:

Nonetheless, competent masks could prove vital in the control of a pandemic that overwhelms our health care system and paralyzes our cities. Availability of masks might allow some measure of confidence for essential services to continue. Masks have an indefinite shelf life and could be pivotal in responding to a potential bioengineered microbial event, such as smallpox and tularemia. Ensuring an adequate, readily available supply of masks is critical.

I’m not sure I agree, for various reasons, but I wanted you to see their opinion. They also make interesting comments about another technology I am more optimistic about, ultraviolet germicidal irradiation (UVGI). UV-C light is an effective germicide for influenza virus, although at that wavelength potentially dangerous to exposed skin and eyes. Systems that effectively irradiate the part of a room above the head work because there is usually a rapid and efficient exchange of air between the lower and upper portions of indoor environments. While this exchange is relatively rapid (around a minute), a good cough or sneeze can get to you before that, so this is not a panacea. But for environments with high exposure risks (patient rooms, emergency rooms, nursing homes, etc.), UVGI seems like an important and underutilized technology.

One of the readers who pointed me to the AJPH paper was the Marketing Manager for VIGILAIR Systems, Inc., a maker of UVGI units. He was quite honest and straightforward that he was engaged in shameless promotion of his company’s product and said he understood if I passed on writing about it. I almost did, but then decided that it fitted in with the rest of the post. Moreover much of what we read (and post on here) in the conventional press has been carefully placed there by marketing people much less honest than this reader. This is not to encourage anyone else to do this, but I thought it of sufficient interest to tell you about this. I’ve warned you about the source:

VIGILAIR Systems, Inc. announced the results of a study in which Ultraviolet Germicidal Irradiation (UVGI) was used to deactivate the Avian H5N1 virus, commonly referred to as the Bird Flu virus. This study was jointly funded by VIGILAIR Systems and a number of Wall Street based financial and insurance institutions that are concerned about the disruptive effects of a pandemic on business continuity.

Independent laboratory test results show that UVGI effectively deactivated the H5N1 virus. The study tested UVGI’s ability to deactivate the Vietnam strain of H5N1. This is the first time such testing has been performed on live H5N1 viruses, not surrogate microorganisms. (Vigilair Systems, press release)

The company is marketing it as a means to reduce hospital acquired infections and improve indoor air quality. There is some evidence for the former, not much for the latter as far as I know.

It’s another tool, one that seems more useful to me than mass stockpiling of masks. That’s an opinion, not fact. Your mileage might vary.


  1. #1 TEJ
    April 10, 2007

    Can anyone shed more light (excuse the pun) on UVGI? Inactivation rate would be a function absorbed dose, so two issues come immediately to mind. First, the UV intensity will drop off as the square of the radius, that is a particle 2 meters from the lamp receives only 1/4 the dose of a particle 1 meter from the lamp. Second, the time the particle spends in the beam is critical, with particles farther away needed more time to absorb a lethal dose. I would like to assume that these obvious issues have been satisfactorily addressed by the researchers and manufacturers, but have not seen them discussed in forums like this. I’ve seen these lamps in health care settings and wondered, do they really work?

  2. #2 revere
    April 10, 2007

    TEJ: The issues you discuss are well-known and have been investigated. There are two kinds of evidence that they work. One is experimental data using actual pathogens or surrogates (and data on natural UV); the other is from a few epidemiological observations (some, I believe, are cited in the Weiss et al. paper in AJPH, to which I refer you for some data on UVGI). This has also been examined in terms of bioterrorism protection, so that’s another literature to look at.

    UVGI works, but the key question is whether it would make much difference in a pandemic situation or not. You wouldn’t want to use it in every room in every building, you cannot use it outside and there is a small but perhaps crucial lag between emission of infective particles in the lowre part of hte room and inactivation in the upper part of the room. So the question of efficacy remains open.

  3. #3 gilmore
    April 10, 2007

    I’m calling bulls**t on this statement:
    Even if all of these variables are negligible, there is still the effect of gravity pulling down on the mask. (Weiss et al., AJPH)

    Come on now. Yes there are variables, as the straps anchor the mask / respirator to ones face. There positioning and adjustment (loosen – tighten) determine how it “rides” on the face, but to bring up the law of gravity makes me wonder if these guys are stretching to make a point or just don’t know what they are talking about.

  4. #4 claire
    April 10, 2007

    Why isn’t the wearing of surgical or cloth masks by everyone being promoted? We keep saying they protect others as if that’s a drawback. Nothing we’re able to do at this point is a failsafe, but decreasing risk seems preferable to not decreasing risk. If apparently well people (who may be shedding virus but don’t yet know they’re going to get sick) all wear some sort of mask when in public or dealing with each other transmission seems likely to decrease.

    re uv light … can anyone tell me if it’s a particular kind of bulb? Can the kind meant for gardening or for preventing SAD be used? Does this research indicate that a person caring for a sick family member could stand under a uv light for a certain length of time after leaving the sick room and hope to decrease the risk of carrying germs into the rest of the house?

  5. #5 revere
    April 10, 2007

    claire: Many people will wear such masks, which is fine. But it is easily misunderstood that they are protected with them and they are not. I don’t discourage knowledgeable wearing of a surgical mask, although for most people it will mean nothing as they are not infected.

    The lights are a particular kind and the UV radiation they emit is harmful. They are not radioactive, however. So you don’t have these lights and cannot easily buy them as a normal consumer. They disinfect only the volume of air they irradiate at that time and cannot be used “afterward,” as you suggest. Nor should you stand under them. They can harm you. They clean the air.

  6. #6 claire
    April 10, 2007

    Thanks for the explanations, Revere. BTW, I appreciated your bookstore/virus analogy, as well. The fog cleared!

  7. #7 M. Randolph Kruger
    April 10, 2007

    Claire-Military masks for instance are not molded to ones face, they keep trying until you get one that fits you. Then its yours for the duration. Its kept inside of the supply area of every unit in what is known as a mobility bag. It also has your chemical suit and the only protection from bio is the mask itself. The surgical masks as pointed out are not to keep virus or bugs out, they are designed to keep your stuff in. So the outsides of the mask would be contaminated as you pull air thru it to your face. In fact your inhalation will pull it to your eyes and skin around your nose, eyes and mouth.

    Revere has many times but not countlessly reported on the eyes as another infection point, so what do they got for that? Only full face plate masks which are VERY expensive for a family of five and giving everyone in the US one would be off the scale for pricing. This is a personal issue and you wont even need one if you take your nuclear family unit and put it into the house and keep pets in or out, but if in they stay in, out they stay out. For you to do this you have to have enough supplies to be able to stay in and a bailout position to run to if something gets out of control in a city, e.g. fire or riots. Not to say either will happen but you have to have your ducks in a row to do it. That truly would be when a mask is needed.

    If you HAVE to go in to work then the employer by law has to provide you one-OSHA requirement in the US. Biohazardous environment and training. That training will be provided about 15 minutes AFTER the pandemic is over. Dont go into a flu laden environment because YOU HAVE to work. If thats the case then you have to get a pine box ready for yourself too.

    AI virus is very unlikely to be floating in the wind although they report it in dust and feces. It also does really nicely for a long time in the dirt thats in the 30’s during winter.

    UV lights are known to kill virus. But there is a major problem that was being addressed by Sen. Bill Frist who left as Senate Majority Leader last year and that is electric power. If you live in the NE, SE into Florida or the West around LA there is a good possiblity that the power grids will snap. There is a 25 day supply of coal at TVA for instance but that would only take two plants off line and they have nukes to pull up the slack. The northeast is much different, they have a lot of coal/gas fired plants. ConED has dozens and a few dams, but mostly coal/gas fired plants. Cant make electricity without electricity kind of thing. If its gas fired you have to have pumps to move the gas from places like Texas or LNG freighters in Boston and New York harbors. Not a lot of people are going to want to go to work to do the necessary and thats where the real heroes are going to start falling out of the woodwork. If the infrastructure of power, gas, water, fuel stays together then this UV is a good idea. If not the lights go off.

    Gil-No not really on this gravity thing. When you lean over the pliable seal slides on your face and the mask leans forward with you especially at the bottomand stretches the seal even further. If its not worn properly (tightly) the seal pops away and you know what happens after that. Hence the reason for me saying before that fit is everything. In winter you couldnt get that seal to pop on 30 degree day with the heat your breathe makes. On a 90 degree day, that mask is as supple as a baggie. Oozing almost. It fits better in the heat but you have to make sure its tight and that irritates the hell out of you.

  8. #8 Hank Roberts
    April 10, 2007

    UV — I’d welcome thought about what’d be useful. Give us some lead time and we can build our own, if there’s a use for them.

    How much UV-C would bounce off a painted white ceiling and reach the eyes of people standing in the room? Or in bed?

    Subscribers to Nature will be able to read this:

    “Device physics — A bug-beating diode

    “A small-scale, low-power light source emitting in the UVC range could therefore be useful for sterilization applications. …”

    I’d wonder if one good use for this sort of thing might be treating _exhaust_ air from a respirator or pulled out of a tent over someone who’s coughing, assuming the rest of the room could be cleaned once in a while.

    Scary how many gadgets you find if you just Google — lots cheap on ebay (sigh).

    Any unshielded mercury-vapor light is a strong UV-C source; the ones in the hardware store carry the big warnings about not illuminating them until they’re inside the heavy glass shields that filter the output.


    And mercury vapor’s the light source in any fluorescent tube, hidden behind the phosphors that step most of the photons down in energy.

    Here’s one such in a battery water sterilizing gadget:

    You can keep a lot of battery operated gear going as long as there are automobiles to borrow batteries from in an emergency, and bicycles to hook to alternators to recharge …. but deciding it’s worthwhile would have to be done well in advance to trade off the effort and distribute plans for these.

  9. #9 marquer
    April 10, 2007

    Revere has many times but not countlessly reported on the eyes as another infection point, so what do they got for that? Only full face plate masks which are VERY expensive for a family of five and giving everyone in the US one would be off the scale for pricing.

    In unpleasant particulate environments, when there was no other ocular PPE to hand, I have used a simple pair of clear swim goggles with an elastic strap. With success.

    Would that provide protection against conjunctival infection comparable to that of a full-face respirator? It would not.

    Would it be far preferable to going entirely unprotected? In my book, it would.

    Such goggles have definite downsides. They would be difficult to decon, and they are costly enough to not lend themselves to a single-use disposal model. You want for this stuff to be disposable, so that people can take the kit off and drop it straight into a sterilizing waste container (e.g., a bucket filled with bleach). Per unit cost of a goggle would be five to ten times that of an N95.

    My own thinking on the mask issue breaks down by zone, if you will. Anyplace with a large number of infected or possibly infected persons is the proverbial hot zone, e.g., a hospital or an evacuation center. N95 protection would be inadequate when every single intake of breath is likely to contain airborne virii. What hot areas call for is a fullface or a hood.

    HCWs, police, firefighters, critical infrastructure personnel in hot zones should not be relying on N95! Nowhere near good enough.

    But not every single place on the planet is going to be hot. And that changes the rigor of PPE requirements for places which are not.

    Inside of an isolated structure like a single-family home, as long as no one is going in or out, and everyone in residence is still healthy, no mask use at all would be required. That’s the “cold” zone.

    And then there will be “warm” zones, areas out in public that are not filled with obviously sick people, where there will be civilians out performing necessary errands. It will *not* be logistically or operationally possible to keep everyone isolated indoors at all times. The general population is not and cannot be prepped to that level.

    Yet we have the possibility that infected individuals who are thus far asymptomatic may be moving around in those warm zones.

    In that context, increasing the protection of ordinary civilians while out doing things like fetching supplies, in a warm zone, N95 may make some sense. Would FFR or hood be better? You bet. Is it possible to make provision for FFR or hood given realistic cost and time constraints? My bet would be, no.

    Another thought has suggested itself with regard to warm-zone infection control and lightweight masks.

    It has been noted here at EM that the actual function of a surgical mask is not to protect the HCW wearing it from inhaled hazards, but to prevent the HCW’s exhalations from contaminating patients. However, although not by design, surgical masks do give the wearer some modest protection against large inhaled particles.

    An N95 is designed to protect in the other direction. It is meant to keep an uninfected person safe from possibly infected people nearby.

    But if the N95 exhalation system were redesigned (to dampen the velocity and to trap particles), that might also mean that an infected person wearing that mask would be less likely to act as a successful spreader.

    Consider someone who sneezes a sneeze containing live virus while wearing such a safe-exhalation mask. The radius of dispersal will be far less than if they had sneezed maskless into the open air.

    Current N95 designs vary a great deal. Some have exhalation valves (which are necessary for wearing comfort and for a good seal, but which do not lend themselves to containing exhaled breath).

    A good start would be to have the mask engineers devise a new standard, say, F95 or F100, with the specific intent of improving warm-zone safety during a pandemic. Exhalation diverters would be obvious. More extensive fit customization would help. You could even bag them with single-use goggles if the price point of the latter could be worked down low enough.

  10. #10 M. Randolph Kruger
    April 10, 2007

    Marq-Fyi. The military uses the newer version full face masks with the N95 NBC filter. They are worn by the docs and nurses in sim-bio environments. Specifically they use the German made Draeger filters under contract to NATO who farms the work out to the US and other manufacturers. All have double pull valves which vent back out the front the same way it goes in.

    Would I sit around in a germ laden environment with one on? Only if it were necessary as the manual states that everyone should move to a cleaner environment whenever possible. I other words they know they are going to take casualties. I wouldnt go into a hospital say with only that on. I would wear a suit because the mask does move around and if virus is on your skin and the masks moves back and forth it is likely to move some inside of the mask. Enough to infect? I dont want to test the system.

    Hoods were found to be ineffective in previous tests except to escape from a situation. As for HCW’s, fire and police, well thats part of the hazards of the job. Periodic decontamination without taking the equipment off is also good. Good washdown basically removes the surface contamination. I can stay in a suit and mask all day long if I have to.

    I wont be in a surgical mask under any circumstances in any biohazardous environment. It might protect, it might not. The full face plate masks are the best thing going and there are going to be failures of even those.

  11. #11 Earl E.
    April 11, 2007

    I have been wondering——after THREE YEARS of WARNING—why

    are there NO clear answers and definitive information on

    Personal Protection Equipment for people?????????????

    I still believe costume adhesives that require remover could

    work for a ONE SHOT N95 respirator fit issue in an EMERGENCY.

    MRK—particles go in the filter of a respirator and stay there. They are


    If you very carefully remove the respirator with gloves

    it will not pose a hazard of releasing virus into the air.

    If no glue is available—placing petroleum

    jelly(vaseline)along and under the edges of the N95 would help.

    WHO said years ago—once the pandemic blows—N95s are NOT

    recommended. I was stunned. We have had YEARS to manufacture and stockpile tons of N95 respirators!!!!!

    The only reasons I can think of are:

    1. USA is too cheap to spend money on stockpiling respirators.
    (other countries have).

    2. Everyone should stay home unless they are desperately needed for society to keep functioning. NO N95 respirator for you—-if you are a just a body taking up space!!!!

    3.The H5N1 virus is found in other sources—like water, insects, food, dust, etc., so that respirators WILL be useless. THIS IS THE REASON I PRAY IS WRONG!!! If this is the case—it was nice knowing you all.
    See you in HEAVEN!—(sorry Atheists–so sorry, Revere……)

    If it keeps on like this with the crappy and unreliable Personal Protective Equipment stories—no one that is desperately NEEDED for society to function will come out either. They will “Get out of Dodge” as soon as possible.


  12. #12 Tom DVM
    April 11, 2007

    Earl E.

    Just wanted to say that your post above is a wonderful piece of writing…I could only wish to write that good.


  13. #13 marquer
    April 11, 2007

    1. USA is too cheap to spend money on stockpiling respirators.
    (other countries have).

    Decades ago, Israel bought huge numbers of military-grade full-face respirators for its civilian population.

    This was back in the day when Saddam Hussein actually had chemical weapons and potential delivery systems, which is to say, before the end of the first Gulf War.

    They ran up against the whole question of how to get numbskull civilians to properly don and doff a complex mask. An Israeli who lived through that period told me that the authorities blanketed the television with constant detailed PSAs which showed clearly how it was done. Although the deployment never got the acid test (or the gas test), it seemed to work out reasonably well.

    Note that they spent a huge amount of money on that project.

    Randy: equipment made by Draeger has been well spoken of by people I know who have used it.

    Hoods were found to be ineffective in previous tests except to escape from a situation.

    I am aware of “escape hoods”, relatively cheap and simple single-use units for a fire or a chemical release, but I am also aware of full-time protective hoods which are meant to be worn for long periods of time, externally decontaminated, doffed, and reworn at a later time.

    The hoods don’t work passively as a fullface would. They require either supplied air from a line, or a PAPR belt/backpack unit. The logistical complexity is obvious. And the vulnerability to electric supply disruption is clear.

    There are a couple of reasons why hoods are opted for. They cut the risk of face seal deficiencies. A sloppy or untrained person is less likely to screw it up. Facial hair is a nonissue. Facial chafing is similarly a nonissue. The hood drape gives a large smooth surface to which something like a Tyvek garment can be taped securely.

    Hood systems get used every day in applications such as spraying isocyanate mists. Where, if there is a leak, you are in real immediate trouble. I’d rather take a lungful of H5N1. At least that way I would have a few hours to say goodbye.

    As for HCW’s, fire and police, well thats part of the hazards of the job.

    Yikes! I don’t want for people in those critical positions to be told to “Suck it up, shoulder the risk, and if necessary die like an aviator.”

    Hope is not a plan. But neither is hoo-ah. Esprit and professionalism only go so far.

    There is a magnifier effect of which we should beware. When an HCW falls ill, and either dies or is too incapacitated to work, how many prospective patients will then go without care which that person could have provided?

  14. #14 M. Randolph Kruger
    April 12, 2007

    Marq-its not so much that the government is cheap, its really more states problem as the Feds have already told the states they will be on their own. Front end, up front and acknowledging that spending boxloads of money isnt really going to change the outcomes. The supposition is that Tamiflu will keep some alive. But if you get it then what?

    Respirators, ventilators, etc are going to mean squat if this comes rolling in. It will be a bug tsunami and while I agree with Revere on part of his suggestions, I dont think that beefing up the healthcare system will change too many outcomes. It would be miniscule if its high path. Does that mean that we should hold the federal government responsible for the outcome? That will be debated for years afterwards. The really big question is going to be, “What did I do to ensure my safety?”

    If you havent prepared with food at the least, or if you ascribe to the N95 paper mask with tape, or the respirator full face masks, have plenty of filters on hand, decontamination chemicals and facilities then thats a question that will answer itself immediately upon your need for something. Need to eat, need to drink, need to go out and work in this if it comes. Its going to be finally the one thing that levels the playing field in this country that has gotten used to government providing everything for them. Poor people will go, rich people will go (in lesser numbers), the middle class will go and mostly from the same reasons.

    I wouldnt get too excited about the government not spending get this 22,500,000,000 dollars for respirator masks. This doesnt count additional filters for four months. It doesnt matter. Someone wouldnt wear it, someone would wear it poorly, many would still get infected. Its just an inevitability thing. I would rather them spend 22 billion for food supplies but the logistics of that are that its impossible. If it comes Marq, my bet is that we lose as many to starvation as we do to the flu if its high path and in the numbers we are seeing now. Second or third wave would start when people go out to forage for food. Your realm of control will be from your doorstep back into the house, not beyond if this comes. You HAVE to be a fortress of all things. Masks, food, repair tools, fire fighting, etc. No this mask thing doesnt bother me one bit. Its just a check off thing on the list for survival. Get one or not. Prepare for all things and not just a mask. Prepare and hope for the best outcome which is that you survive it.

  15. #15 Earl E.
    April 12, 2007


    Your recommendations, MRK, are right on. I also feel the pandemic will be very severe when it comes. How did you calculate that 22.5 billion number?

    You are way over what the true cost of what respirators would be, my friend.

    But, I really don’t care.

    When this pandemic blows—no one is going to have time to blame anyone or anything.

    Desperation will result in COOPERATION, I hope.

    Societies that get along survive.

    As Abraham Lincoln said—-“A house divided against itself cannot stand”.

    Right now—there is no solution to stop a severe pandemic event.

    People are working hard at all levels on it. I have been thinking about it for years.

    I have no solution—–not even for myself………

    The pandemic has held off, (by some miracle!), for years.

    My plan is to survive until there is a vaccine that works.

    Focus on survival—food, water, coping with no electricity, getting extra supplies of “need to live” medication—be a PIONEER in your mind’s eye.

    People survived thousands of years without electricity. We need to learn how to do that again.

  16. #16 M. Randolph Kruger
    April 12, 2007

    Earl-took the population of the US and dropped the going price of hoods/masks to a 75 dollar per unit cost, then multiplied that out. Of course its not totally scientific because it included babies and kids that even a hood wouldnt fit over if you superglued it to his butt. Its a good indication of the costs though.

    Hey Earl, I survived in central america for several years without electricity. I can remember stepping back into the world and almost freezing to death at 80 degrees in an air conditioned car for the first time in three years.

  17. #17 Marissa
    April 12, 2007

    Good post, Revere. On the UV lights one has to remember that air/surfaces in shadow of the lamp(s) will not receive radiation.

  18. #18 Tom DVM
    April 13, 2007

    It should be remembered that a very expensive UV light system at the ceiling is not going to protect a healthcare worker from a patient on a bed, coughing in their face.

  19. #19 marquer
    April 13, 2007

    The UV light idea may have some genuine utility in certain closely restricted situations. There will be certain places which have HVAC systems and where airborne viruses are likely. UV in the air handlers makes some sense. As do HEPA filters — a suggestion from Tom DVM, if memory serves. You can even make HEPA filters out of Gore-Tex so that they can be decontaminated and re-used.

    But it would be sensible to put more effort behind ways to inactivate virii which don’t require electricity, which are easily portable, and which are cheap. UV qualifies on none of these counts.

    My money would be on anhydrous isopropanol in spray bottles.

    A hypothetical disposable mask kit could contain a simple squeeze bottle containing 5ml of isopropanol.

    Doffing instructions: thoroughly mist your gloves, goggles and exposed skin. Take a breath, mist the outside of the mask, wait until you can’t wait any longer, then get the mask off in as close to one smooth motion as you can. (And don’t put the bloody thing back on!)

    Here’s a question: what would make a reasonable simulant for airborne viral particles with which to test such measures?

  20. #20 M. Randolph Kruger
    April 14, 2007

    Earl-OSHA USA in case you live somewhere else has designated the paper/cloth things you hang over your ears as a mask and not a respirator. Respirators is an enclosed system covering the mouth and nose at a minimum and the eyes and head at the maximum. Those particular ones that cover the eyes,nose, mouth are about 120 a piece. I figure that Halliburton would provide them at the discounted price of 75 bucks a piece.

    As for surviving until there is a vaccine that works..Let me see. That would be onwards of a year unless you are government essential or an HCW. Would you really want to to be the government guinea pig for the first out test on a vaccine. Remember Swine Flu. I knew two guys back then that were in the military, forced to take the vaccine and it screwed them up bad. Guillaume-Barre Syndrome made them into cripples.

    Survival is in the house. I think they will prohibit foreclosures for a year after the bird bug comes and they will drop the interest rate to 0% during that time to get the economy moving after its gone. Thats if the bug doesnt mutate into something worse and jump past the vaccine. Lots to consider.

  21. #21 Gerard Sullivan
    April 14, 2007

    A Florida man has patented a portable, rechargeable battery operated UVGI device, currently being evaluated by the U.S. Army, which can protect an individual for hours or days.

    Until now, what hadnt been available is a portable device that protects the user, first responders, health care workers, etc., from both chemical and biological contaminants. This patented portable device works with any NIOSH approved respirator face mask, and is light weight, worn over the shoulder or on the belt, and attaches to the standard respirator mask air inlet. The battery life is up to eight hours and can be recharged using the supplied 110V AC or 12V DC adaptor. To reduce the effects of gravity pulling down on the mask, the canister has been relocated to the portable device housing.

    When a HCW (health care worker) falls ill as a result of a pandemic, epidemic or an act of bio-terrorism, and either dies or is too incapacitated to work, how many prospective patients will be without the care that that person could have provided?

    How it works is incoming air enters the device through a standard respirator canister, and then passes over a UVC tube where the DNA and RNA of the microorganisms is altered making them incapable of reproducing, and therefore harmless. Larger microorganisms such as anthrax spores in the 1 to 3 micron range need longer UVC exposure to render them harmless, these will not pass thru the HEPA, and are therefore trapped and held to receive a lethal dose of UVC.

    It has been proven that when UVC is properly utilized, disease causing microorganisms will be substantially reduced. Scientific reports have documented, that the use of UVC, Ultraviolet Germicidal Irradiation will reduce pathogens and allergens such as; Mold, Mildew, Viruses by as much as 99.999%, which includes Bird flu, Anthrax, Legionella, Tuberculosis, SARS, and Streptococcus, to name just a few.

  22. #22 marquer
    April 14, 2007

    Until now, what hadn�t been available is a portable device that protects the user, first responders, health care workers, etc., from both chemical and biological contaminants.

    Both chemical and biological?

    I am prepared to give credence to the claim that intense UV will inactivate many aerosol biohazards, but I can name a whole bunch of unpleasant chemicals which would not even notice such irradiation. This has the smell of marketing about it.

    However, since the design challenge of the moment is public safety against an airborne pandemic agent, sure, bring it to the table. More details would surely help.

    This approach has similarities to what I mentioned upthread about PAPR supplied air for hoods. (And is, basically, PAPR plus UV.) Technologically complex, costly, and reliant upon electrical service. Many UV sources are pretty much just fragile bulbs. Turn around and smack that belt unit on a corner and foop, you need a field replacement right away.

    If it in fact works as asserted, it may have utility and may make economic sense for use in intensely infectious zones. Manufacturing these units by the hundreds of millions gets into the realm of severe cost constraints.

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