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  • Masks & suggestions for how to use them

    From the New York Times

    http://www.nytimes.com/2006/10/25/op...th&oref=slogin

    Face Facts
    By LAWRENCE M. WEIN
    Published: October 25, 2006

    Stanford, Calif.

    DESPITE all the attention given to anthrax and smallpox and potential weapons of mass destruction, pandemic influenza is probably the world's most serious near-term public health threat. If a strain similar in effect to the 1918 Spanish flu (which killed tens of millions of people worldwide) emerges in the next several years, it is highly likely that an effective vaccine will not be available during the pandemic's first wave, that we won't have enough antiviral drugs for large-scale prophylactic use, and that hospitals will be too overwhelmed to treat most cases.

    Consequently, as in 1918, we will need to combine medical efforts with voluntary and forced social changes ? closing schools and churches, canceling public gatherings, keeping workers at home ? to hinder the flu's spread. Our government must draw up a plan for educating the public about effective nonpharmaceutical interventions like hand washing and face protection like masks.

    A prerequisite for doing so is determining the biggest culprit in spreading influenza: droplet transmission, in which an infected person sneezes or coughs directly into the mouth, nose or eyes of someone who is susceptible); contact transmission, in which virus is transferred via hands either directly, say, through a handshake, or indirectly through an object like a doorknob; and aerosol transmission, in which evaporated virus-containing particles are inhaled.

    Remarkably, this issue has not been resolved: the Department of Health and Human Services' Pandemic Influenza Plan states that "the relative clinical importance of each of these modes of transmission is not known." As a result, the government enthusiastically endorses frequent hand washing ? which would reduce contact transmission, and costs nothing ? but remains noncommittal about face protection. While the government says that it might be beneficial, it doesn't make respirators or masks available. Yet face protection would guard against aerosol and droplet transmission, and even reduce contact transmission by making it difficult to place fingers into one's mouth or nose.

    A Stanford graduate student, Michael Atkinson, and I recently performed a detailed study of the routes of transmission, using data on influenza and on rhinovirus, which causes the common cold. Our findings suggest that the dominant mode of transmission for influenza is aerosol ? implying that hand washing will make little difference. This is consistent with the views of leading researchers several decades ago, views that have somehow been forgotten by the public health community.

    We found that ventilation, like placing a fan in an open window, and humidifiers (most influenza strains survive in the air for much less time when the humidity is raised to about 65 percent) can reduce transmission slightly. Sleeping in separate bedrooms (and working in separate offices) can help even more.

    But the single most effective intervention is face protection. And because roughly one-third of influenza transmissions occur before an infected person exhibits symptoms, these precautions should be taken whenever people are in the same room throughout the pandemic period.

    There are two kinds of face protection: N95 respirators, as worn by construction workers, for instance, and surgical masks of the sort worn by dental hygienists. (The respirators cost roughly a dollar apiece, the surgical masks 10 cents.) Their efficacy in preventing aerosol transmission depends on three factors: the extent to which the face filter prevents virus particles from passing through, how tightly the device fits and ? most important ? how long people can be coerced into wearing them.

    To our surprise, we found that the filters in surgical masks, although not as good as the filters in N95 respirators, are still quite effective. And although a surgical mask fits much more loosely and allows more leakage, it's also more comfortable ? and therefore likely to be effective because it's used more. Wearing nylon hosiery over a surgical mask essentially eliminates the face leakage, making this combination a practical, albeit macabre, alternative. The less comfortable N95 respirators would probably result in lower compliance.

    The government doesn't stockpile masks and respirators, and the manufacturers aren't able to produce a huge number of them quickly. But the way forward seems clear: the government needs to build up a supply of respirators and masks just as it does with vaccines and antivirals. It should first hire a whiz-bang design company to create, within one month, a surgical mask that comfortably adheres to the face, and then decide on the appropriate mix of respirators and masks. Next, it needs to sign contracts with manufacturers to stockpile masks and respirators, relieving the manufacturers of liability issues.

    Although there is very little technological risk involved (masks and respirators are easier to make and safer to use than vaccines), several issues need to be ironed out. First, the effectiveness of N95 respirators and masks varies widely. The government needs to educate the public (the brands are anonymous in the published studies) and should stockpile only the most effective brands.

    Also, if respirators and masks are discarded daily, as they are in many hospitals, the national demand during a three-month pandemic could be 10 to 20 billion, and the cost for respirators for a family of four several hundred dollars. Such waste isn't necessary. The virus does not survive longer than a few hours on the material used for masks and respirators, so they should be re-used until they disintegrate.

    The government and the public health community must switch mindsets, from the current perspective of protecting workers paid to do a dangerous job everyday, to that of providing citizens with the tools to best protect themselves during a pandemic.

    It may take 18 months to build a stockpile of respirators and masks, so there is no time to lose. The American people's faith in their government will be seriously undermined if, along with larger measures like school closings, it cannot provide effective face protection for its citizens during a deadly pandemic. Masks and respirators may be our main lines of defense during a pandemic.

    Lawrence M. Wein is a professor at Stanford's graduate school of business.

  • #2
    Re: Masks & suggestions for how to use them

    > Face Facts
    > By LAWRENCE M. WEIN Published: October 25, 2006
    > Stanford, Calif.
    ...
    > hundred dollars. Such waste isn't necessary. The virus does not
    > survive longer than a few hours on the material used for masks and
    > respirators, so they should be re-used until they disintegrate.
    ...

    I'll throw this comment out for feedback from the medical specialists, as my knowledge is limited to personal protective equipment.

    The effectiveness of a face mask decreases as the mask material becomes saturated, so re-use or extended use is not wise if you are in a contaminated environment. This is exacerbated if you are wearing a mask in a cold environment as there is increased condensation on the mask material. There are N95 type masks with an exhaust vent that protects the filtering surfaces from compromise by moisture. (I've worn N95 masks outdoors in the Canadian winter and had most of the filter surface blocked by frost in short order)

    The WHO recommends changing surgical type masks every two hours and N95 masks every 6-8 hours. (http://www.wpro.who.int/sars/docs/masks/masks_faq.asp)

    A second observation is that the author is speaking about surgical masks and not the much less effective paper masks which are also available. Surgical masks have a superior filter and usually offer fluid protection. Some N95-type masks also offer fluid protection.

    There are also more efficient face masks available that offer almost 100% protection against particulate matter including aerosols. To move above the N95 level usually requires moving to a half-face mask with cartridge filters. These masks offer less breathing resistance, no concern about filter media becoming saturated and less speaking resistance. They do require proper fitting and some maintenance. In an environment with spray hazards they may also need surface decontamination (as opposed to disposable masks which can be incinerated).

    Of course, any mask with an exhaust vent offers no protection to other people as the wearer's exhaled breath is unfiltered. The question of care-givers infecting patients is an important consideration that must be assessed in each environment.

    Those involved in care-giving where patient protection is required should use a properly fitted unvented N95-type mask or, if that is unavailable, a surgical mask. Masks should be changed on a regular basis as advised or whenever the filter material becomes compromised (damp, splashed with fluid or contaminated by touch).

    Where there is no concern about the care-giver infecting a patient, the vented N95 mask or the higher efficiency half-face masks can be used with N, P or R-100 filters. When properly fitted these will provide the highest level of respiratory protection.

    Comment


    • #3
      Re: Masks & suggestions for how to use them

      sameo416,
      Thank you for providing this information!
      "In the beginning of change, the patriot is a scarce man (or woman https://flutrackers.com/forum/core/i...ilies/wink.png), and brave, and hated and scorned. When his cause succeeds, the timid join him, for it then costs nothing to be a patriot."- Mark TwainReason obeys itself; and ignorance submits to whatever is dictated to it. -Thomas Paine

      Comment


      • #4
        Re: Masks & suggestions for how to use them

        Yes, thank you for the observations, sameo416, and welcome to FluTrackers.

        We will face a critical shortage of masks once a pandemic starts and we need to discuss and explore all alternatives now while we still have time.
        http://novel-infectious-diseases.blogspot.com/

        Comment


        • #5
          Re: Masks & suggestions for how to use them

          Welcome samo416 glad you are here!

          What do we know about the nano masks that I am now hearing about. Is that the n-100 you mentioned or is that something different?
          TM

          Comment


          • #6
            Re: Masks & suggestions for how to use them

            Welcome Sameo416.

            I have some questions and observations from a lay person (mask-wise anyway):

            The surgical masks appear to me to look as if they do not have a secure fit. Is this true?

            Are the virus particles of H5N1 small enough to penetrate the N95? N100?

            What are the most effective alternatives to masks if none are available? Most of the world will not have access to Nanything.

            Also, if this is in your field of expertise:

            Under what circumstances would protective eyewear be worn? And which type is the best?

            What type of gloves are the preferred? And if there are no gloves available, how often, with what, and under what circumstances should the hands be washed?


            Thank you very much in advance for any information that you have on these items.


            Again welcome,


            Sharon

            Comment


            • #7
              Re: Masks & suggestions for how to use them

              Welcome Sameo416 and thank you for sharing your expertise.

              Snowy

              Comment


              • #8
                Re: Masks & suggestions for how to use them

                Gracious, that is quite a set of questions. I?ll do my best. Please note I?m not a medical specialist but an electrical/aerospace engineer with much safety training from industry and health-care and nuclear, chemical and biological defence training from the military. My experience is mostly in the practical aspects of self-protection and survivability (we called it "STO" - survival to operate).

                >We will face a critical shortage of masks once a pandemic starts and we >need to discuss and explore all alternatives now while we still have time.

                CDC has a good general-public info sheet on masks and respirators available at: http://www.cdc.gov/elcosh/docs/d0500...0/d000570.html

                Particulate masks (like the N-95) have a very long shelf life if properly packaged and stored. There is no reason why you could not store a few boxes of N-95 masks in your ?just in case? cupboard.

                In buying any personal protective equipment ensure that it is certified ? for masks look for NIOSH labelling. This indicates the mask has passed independent testing.

                >What do we know about the nano masks that I am now hearing about. Is >that the n-100 you mentioned or is that something different?

                I had not heard of the ?NanoMask? before but did a bit of research. The company info is available at: http://www.respaide.com/index.htm

                This is a half-face mask with a replaceable filter. The company reports that the filter is 99% efficient but it is unclear what size of particles and what airflow they are using to prove that claim. They mention the filter is tested down to 0.027 micron particle size (a smaller virus) but I can not find a clear statement of what filter efficiency has been proven at that size.

                The filter has been treated with a rudimentary ?nano? particle which is hostile to living pathogens. The company reports that this prevents pathogens from existing and reproducing on the filter surface.

                However, the filters have only a two-year shelf life so could not be easily stockpiled for any length of time. I also note that these filters are not yet certified by an independent test agency and so have not received NIOSH approval. The company claims a high level of performance but independent certification is really necessary before you start trusting your safety to the filter (it may be a great product, but I trust things that are certified).

                A word on filter efficiencies: masks are certified to a NIOSH (National Institute for Occupational Health and Safety) standard that rates masks as providing a certain level of filter efficiency for a certain size of particles at a certain air flow.

                So, the N-95 masks often spoken of will remove 95% of particles with a median diameter of 0.3 micron or larger at an airflow of 85 litres per minute. That is a laboratory-qualified number that assumes the mask is properly fitted and the filter material is not compromised (for example, by being saturated).

                No simple filter system will remove 100% of all sizes of particles. The idea is to reduce exposure and thereby reduce the probability of encountering a sufficient quantity of a pathogen to transmit an infection. To achieve 100% protection requires either a self-contained breathing system or a high-quality multi-stage filter.

                >Are the virus particles of H5N1 small enough to penetrate the N95? N100?

                Yes, any of those masks can be penetrated by a virus as the mask pore size is larger than most viruses. For example, influenza virus is listed as ranging from 0.08 to 0.12 microns in size which is well below the test particle size of 0.3 microns.

                The reason 0.3 microns is used as a test standard is that you will rarely encounter a pathogen that is airborne by itself. Pathogens are usually airborne in droplets of liquid or along with dust (think of the cloud of particles created by a sneeze). The idea is that if you filter out the dust and droplets, you also catch the pathogens.

                The idea that individual viral units are floating around is not something I?ve ever seen documented. Unless something has been highly processed to exist in a form that travels on very fine particles it is not likely these will be encountered in a care-giver situation. You will recall back in the anthrax scares the media was often speaking of the so-called ?weaponized? pathogens ? those which had been processed to remain viable while being easily dispersed.

                Transmission of influenza is done by airborne droplets containing the virus which are around 5-10 microns in size. Those droplets decrease in size after being expelled due to evaporation, and the smaller the particles in the aerosol the longer they tend to remain suspended in the air.

                I?m not a disease or pathogen specialist so that is about the limit of my knowledge in that area (my training on bio hazards was military, so it was less on the why and more on the how of self-protection).

                I have read several recommendations that persons working in areas where they may be exposed to hazardous pathogens should wear at least an N-95 mask, and not a surgical mask. For example, http://www.cdc.gov/ncidod/eid/vol12no11/06-0426.htm .

                >The surgical masks appear to me to look as if they do not have a secure fit. >Is this true?

                All masks only work as well as they fit the wearer, and fitment of masks requires some specialty training. The surgical masks are among the poorest fitting masks ? usually ?one-size fits all? based on what box happens to be open on the shelf (I?ve only ever seen one cart in a hospital that had 3 sizes available). There is air leakage around the sides of the mask which is made worse if it is not securely fitted.

                The N-95 molded masks have a better seal but you have to identify which size fits your face and then wear it properly. The best seal will come from a silicone half-face mask that has been fitted by a mask specialist.

                A note on higher efficiency masks. The N-100 masks have a higher filter efficiency than the N-95 (99.9% versus 95%) but there is a practical trade-off. Typically when the filter efficiency is higher you have greater the breathing resistance (and cost). The mask is less comfortable to wear and more limiting on the amount of exertion you can undertake.

                >What are the most effective alternatives to masks if none are available? >Most of the world will not have access to Nanything.

                You can achieve some protection from improvised masks, since most of the threat comes from rather large airborne droplets. There is an interesting article out of the University of Pittsburgh that outlines how to make such a mask from t-shirts.
                http://www.cdc.gov/ncidod/eid/vol12no06/05-1468.htm

                >Under what circumstances would protective eyewear be worn? And which >type is the best? What type of gloves are the preferred? And if there are >no gloves available, how often, with what, and under what circumstances >should the hands be washed?

                There are basically three paths for transmission of a pathogen ? direct contact (i.e. fluid exchange); through the air as an aerosol or droplets; or through second-hand contact of a contaminated surface or person (and then through the skin by a cut or cross-contamination of a mucus membrane).

                The goal in preventing infection is to break those paths. So, during flu season avoiding sick people and washing your hands regularly (while avoiding touching eyes, mouth and nose) helps break the direct contact, airborne path and the second-hand path.

                Health care usually recommend that protective eyewear be worn whenever there is a splash hazard (blood sampling or inserting an IV) or an aerosol hazard (sneezing). The eyewear makes it more difficult for the airborne particles to find their way to your eye and into your body. Likewise for gloves.

                For most people outside health-care settings it is impractical to wear eye or hand protection. Good hand washing discipline and use of waterless hand cleaners is sufficient. Controlling any personal habits of touching near mucus membranes with hands is also important (near nose, eyes, mouth).

                Wearing such protection (and this includes masks) also requires some training to avoid re-contamination. For example, once a mask has been worn in a potentially contaminated area the mask surface must be considered contaminated and can not be touched. Removing protective gloves must be done such that contaminated material on the outside of the gloves is not transferred onto your skin (there?s a neat trick to this that ends up with the gloves off your hands and inside out but it takes practice).

                The reality is that we?re exposed to all sorts of pathogens everyday whether we?re out in public or working in our garden. Most of that exposure is handled by our natural defences and adding regular hand washing and caution in touching your face is pretty good at preventing transmission of infection.

                I hope that is of some help.

                Comment


                • #9
                  Re: Masks & suggestions for how to use them

                  Thank you very much for this input. Very informative.

                  Comment


                  • #10
                    Re: Masks & suggestions for how to use them

                    WOW you need to publish this as an article. Excellent. Thank you so much. I'll never look at a mask the same way!
                    TM

                    Comment


                    • #11
                      Re: Masks & suggestions for how to use them

                      > Face Facts
                      > By LAWRENCE M. WEIN Published: October 25, 2006
                      > Stanford, Calif.
                      ...
                      > hundred dollars. Such waste isn't necessary. The virus does not
                      > survive longer than a few hours on the material used for masks and
                      > respirators, so they should be re-used until they disintegrate.

                      ...

                      ABSOLUTELY NOT TRUE!!!!!!

                      The influenza a virus (which h5n1 is) can live on surfaces for 48 hours. The following is from a German Study available on PUbMed:

                      Most viruses from the respiratory tract, such as corona, coxsackie, influenza, SARS or rhino virus, can persist on surfaces for a few days. Viruses from the gastrointestinal tract, such as astrovirus, HAV, polio- or rota virus, persist for approximately 2 months. Blood-borne viruses, such as HBV or HIV, can persist for more than one week. Herpes viruses, such as CMV or HSV type 1 and 2, have been shown to persist from only a few hours up to 7 days

                      http://www.ncbi.nlm.nih.gov/entrez/q...=pubmed_docsum

                      I get very angry when these academic "publish or perish" persons write articles that are not only incorrect - but they have the potential of indirectly killing people who read them and believe the trash they write. It's outrageous!

                      PLEASE do not trust everything you read. The informed consumer is the best one. Research the facts and draw your own conclusions. All the data is out there - you just need to go get it.
                      Last edited by sharon sanders; November 1, 2006, 07:17 AM. Reason: changed derogatory references

                      Comment


                      • #12
                        Re: Masks & suggestions for how to use them

                        Here is a nice pdf file on how to fit test a respirator mask:

                        http://www.kcprofessional.com/us/dow...t_test%202.pdf

                        It is from this website:

                        http://www.kcprofessional.com/us/Pro...asks/masks.asp

                        The National Academies of the IOM (Institute of Medicine) did a study on reuse of respirators---and it is NOT recommended. In a pandemic emergency, however, one can place a plastic shield or cloth surgical mask over the N95 to increase its useful life:
                        QUOTE:
                        "However, the following steps would allow a person to reuse a disposable N95 respirator if necessary. A protective covering such as a medical mask or a clear plastic face shield should be worn over the respirator to protect it from surface contamination. The respirator should be carefully stored between uses, and the wearer should wash his hands before and after handling it and the device used to shield it. These steps are intended for reuse of a respirator by a single person."

                        http://www8.nationalacademies.org/on...RecordID=11637

                        Comment


                        • #13
                          Re: Masks & suggestions for how to use them

                          when one N95 filters 95% then I calculate that two N95
                          in a row , maybe in a tube, should filter 99.75%.
                          Or two N100s should filter all except one in a million particles.
                          Breathing resistence is proportional to the surface of the mask.

                          So, shouldn't we be able to build mask-systems of any level
                          of protection ?

                          I also built a mask by attaching the filter to a tube in my pocket,
                          which I can breathe through the mouth whenever someone sneezes
                          or hustles in my neighborhood. In waiting rooms,buses,..
                          Most of the time you won't need a mask but mask on-off-on...
                          is tedious.

                          Hey, my favourite 100% safe mask is a large plastic bag.
                          Take your air with you ! It lasts 10-20 minutes, then you have to
                          exchange the air. It's light but voluminous. Maybe good for
                          crowded elevators, shopping queues,.. but not socially accepted.
                          The mouth-tube-pocket mask is better here, hardly noticed.

                          Or use compressed air as in the diver-bottles,
                          but it weights some kg.
                          You can also get Oxygen in bottles. I tried one for 4l oxygen
                          in a light box for 4 Euro, equivalent of 20l air, sufficient for
                          maybe 5 minutes.
                          I'm interested in expert panflu damage estimates
                          my current links: http://bit.ly/hFI7H ILI-charts: http://bit.ly/CcRgT

                          Comment


                          • #14
                            Re: Masks & suggestions for how to use them

                            "....a large plastic bag..."

                            Please do NOT try this.

                            And remember...do not leave plastic bags around small children.

                            Comment


                            • #15
                              Re: Masks & suggestions for how to use them

                              with the nanomasks, wasn't that all fraud ?
                              I think, I read something like this about emergency filtration products.

                              Searching google... I just found this board:
                              http://ragingbull.quote.com/mboard/b...cgi?board=EMFP

                              haven't read it yet...
                              I'm interested in expert panflu damage estimates
                              my current links: http://bit.ly/hFI7H ILI-charts: http://bit.ly/CcRgT

                              Comment

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