From Flu Wiki 2

Forum: Testing New Reusable Mask for Children

20 March 2006

CityRiderat 22:57

Hope this request is appropriate for the community in this forum.

I am looking for mum and dad here who is interested to try out a new reusable face-mask for children?

It’s a very compact plastic respirator with disposable filter, the plastic body can be reuse many times and only the N95 filter need to be changed. It is more comfortable than most, if not all, N95 mask. My aim is to make it more attractive for children. I want to make it as affordable as possible, the plastic body hopefully cost less than US$2 and the filter should be less than 20 US cents per use.

The idea came to me when I was looking for N95 mask for my son during the 2003 SARS crisis. After some searching and trying different masks myself, I realized that it was not possible to find effective respiratory protection for children and most of the N95 mask for adult are not comfortable to wear for long period of time. I started to work on this project in 2003 during my free time (yes, I have a full time job not related to mask making). Slowly I went through many steps (many many failure) and finally reach the prototyping stage soon (next month).

My idea is to collect as many user feedback as possible in order to improve the mask, before moving into full scale production.

I am prepare to send out limited number of the prototypes free of charge (but you have to pay the postage from Singapore)

Some preliminary information (protoyypes are a bit different) can be found here: http://www.dreamlab1.com/?page_id=4

If you think you can help, please email to me : cityrider AT gmail.com

CityRider

21 March 2006

PirateGrlat 00:28

CityRider,

I looked over your material on the Rainbow Mask, and from what I saw, you have some significant hurdles to clear with regards to your mask design before it is ready to test.

The “trim to fit” idea is interesting BUT materials make a huge diference and I don’t see how you can ensure a good facial seal with the materials in the photos. Most reusable masks use a soft silicone or elastomeric face piece that makes a good seal to the face due to the soft, moldable material.

The idea of having a child’s mask or any mask for that matter where the mask is completely separate from the head strap (as shown on your site)is asking for trouble…people, especially kids, will tend to lose or misplace either the strap or the mask cup rendering the mask useless. Also, the manner in which your site shows the mask being held to the face with a single rubberband type strap makes the mask VERY easy to dislodge simply by talking or turning the head breaking your seal.

You mention in your above post that the mask is made from “plastic” with change-able filters…what type of plastic? If the plastic is in anyway firm or ridged, a child will not wear it long as it will cut into the face and be very uncomfortable if held to the face firmly enough to form a good seal.

re: that seal,

from your website:

“To prevent fogging of glasses, position the headband slightly towards the upper half to ensure exhaled air escape from lower part of the mask rather than near the top of the nose.”

THIS IS A BIG PROBLEM! If your mask fits such that it is able to fog up your glasses or have “exhaled air escape from lower part of mask” IT DOES NOT HAVE A GOOD SEAL.

The definition of a “good seal” is that NO air escapes from anywhere around the edges of the mask at all. If air can escape, unfiltered air can also get in via the same leak so your mask is not actually filtering at the advertized N95 rate. Fogging of glasses and air escaping at the chin are two classic signs that your mask DOES NOT FIT.

Also, What about mask removal?

According to your site, to put the mask on:

“1. Pull the elastic headband over the head and wear it like a necklace

2. Cup the mask over the mouth and nose with one hand. Extend the headband with the other hand.”

You would have to reverse this process to remove the mask.

This is also a big problem, since the strap and mask cup are not attached, it is impossible to remove the mask without touching the outside of it which after wearing is contaminated. Normally, a mask shaped similarly to yours would be removed by lifting the strap at the back of the head and sliding it forward pulling the mask away from the face by the strap so that the mask itself is not touched…obviously, this will not work with your mask. The method needed to remove your mask may be fine if you are only using it to filter dust, but if it is being used for protection against a deadly virus such as bird flu, your mask removal method creates a very high risk of contamination with virus.

re: the filters The filters shown on your mask look very small - what is the expected service life of these filters? Are they moisture resistant? What is the average time to particle penetration? (most N95 masks start to degrade after 30 to 60 mins use in an infectious environment)What is the avergage wear time before the filter becomes clogged?

Have you taken into account the fact that small children breathe more rapidly than adults and the fact that they breathe 15 to 30 times per minute (as opposed to the average adult who breathes 12 to 20 times per minute)may result in the child’s filter degrading from breathe moisture faster than an adult’s ?

Your basic design seems so similar to an adult disposable mask that I must assume that there is no barrier valve between the back side of the filter and the wearer’s breath…if that is indeed the case, if you are promoting this mask for children to wear if/when exposed to bird flu, have you accounted for the fact that the filters will need to be changed every 20 to 60 mins? This would mean that an adult must disinfect the mask frame and replace the N95 filters several times per wearing…how much will the replacement filters cost?

All that cleaning and filter changing would NOT be something the average parent would want or perhaps even be able to to do and as all approved mask disinfectants are things that should be kept out of the reach of children, the kids can’t do it for themselves.

Do the filter attachments actually create an air tight seal with the face cup? How do the filters attach? Most reusable masks have filters that either screw on or have a deep “twist and click” type post that the filters seal to. You stated that your mask folds flat…this suggests that the filters do not have this type of common reusable attachment. If indeed they do not, how do you garauntee an air tight filter seal?

re: reusability of mask

I saw nothing on your website that indicated how the mask is to be disinfected for reuse and what disinfectants can be used with your mask without damaging the mask materials.

For a mask to be considered reusable, the frame must be able to be disinfected after each wearing.

Do you supply extra head straps to be used with the mask the second, third,or fourth time it is used or are your head straps made of some special material that allows them to retain their original strength and hold despite being stretched for a long period of time ? Will the head strap material hold up to being repeatedly soaked in a disinfectant solution?

ALL of these questions would need to be answered before I would ever consider put this mask on a child.

anonymous – at 00:41

Thanks PirateGrl, for spending your time and attention to my request. I can understand most of your concerns and will try to provide answers when I have a bit more time.

For now just need to clarify one fundamental point: the entire mask body act as a one-way valve; when exhile, the edge of the mask release and they become tight during inhale. The result is similar to N95 with a release valve. This design allows much lower retaintion force by the elastic band and is therfore more comfortable.

Let me get back later to give more information.

CityRider

PirateGrlat 00:54

Hi CityRider,

you said: anonymous – at 00:41 “For now just need to clarify one fundamental point: the entire mask body act as a one-way valve; when exhile, the edge of the mask release and they become tight during inhale. The result is similar to N95 with a release valve. This design allows much lower retaintion force by the elastic band and is therfore more comfortable.”

The entire mask is a one-way valve??? This is indeed an interesting idea, but how is this accomplished?

Creating this type of one-way valve in the entire mask would seem to require lining the mask with a non-breathable material similar to the thin rubber-like material that a typical one-way valve is made from…won’t this be very hot and moisture promoting to wear?

I look forward to hearing more about your mask.

Dr C – at 01:59

The Institutes of Medicine (IOM) will be issuing it’s report on masks appropriate for bird flu, including masks for children, sometime next month.

They’ve been researching the options and are now writing it up.

CityRiderat 08:31

Hi PirateGrl,

My answer may become clear if I explain the design intent of the new mask first.

During the SARS crisis my friends working in hospital in Hong Kong complained that the N95 mask was too uncomfortable to wear. I decided to try it myself and start to understand what they mean by “uncomfortable”. I believe the main reasons are following:

1) high stress in the head band over a prolonged period, pain around the ear area (hard to avoid due to the need to ensure a good face seal) 2) exhale air quickly heat up the space within the mask, which covers a large part of the face (filter material is poor heat conductor) 3) fogging of glasses (difficult to fit different face size/profile, easy leakage of exhale air near the nose bridge) 4) more difficult, or irritating, to communicate with each other (due to lost of facial expression, stretch the scope of “uncomfortable” a bit)

All these make most existing N95 mask “uncomfortable” to wear.

Naturally I try to solve all these identified problems, or at least as much as possible. After many failing attempts, I stumble on a radically different concept - why not use the whole mask body as a one-way valve?

If I hold a mask not at the edge (ALL existing N95 masks does), but rather hold it at the top of the mask, than the edge become RELATIVELY “free” to move (e.g. within 0.05 mm). The edges responds to the breathing cycling by expending and contracting slightly, which is collectively enough to perform like a one-way-valve. The retaining force in the head band can be reduced substantially because the negative pressure within the mask helps the mask to close the tiny gaps when inhaling. When the user breath out, the exhale air is quickly release due to the positive pressure now exist inside the mask helps to open the tiny gaps along the edges.

Right now, I hold back the trim-to-fit idea because many previous tester complaint that it is not easy. Another problem, as you have anticipated - the edge cut into the face - will be resolved by a rounded edge along the mask.

To ensure this is working as expected, the choice of material (softness) is a key factor- you are absolutely correct- and this is one of the parameter I want to test during the next phase of prototyping.

The body of the mask is made of non-permeable plastic material, currently I am thinking of PP or medical grade PVC. plastic (thin sheet) is a much better heat conductor than the N95 filter material, therefore the heat trapped inside the mask is much reduced. Some people may not like the feel of plastic touching the face, we have to see how good /bad it is when we have the prototypes.

One bonus of plastic is that I can mould it in transparent color, you can see through the mask and this is easier for communication.

The head band do have the option to be attached to the mask in a slot and will hold on to it unless the user pull it out forcefully. It is also possible to have more than one head band, (or ear loop) to ensure a good seal along all edges of the mask.

To answer your concern of contamination when changing the filter: Most of the virus will be trapped in the filter area because all inhaling air going throught it, the mask body is non-permeable so it should not attract more virus than, say, the rest of the headband. Anticipate the procedure would be (1) to take off the mask by holding the tip of the mask body (2) fold tha mask flat so the inside surface are not exposed, pull out one of the filter and replace it with a new one, (apply force on the edge of the filter rim) (3) flip the mask and pull the second filter and replace it with a new one. (4) put the mask back on. Important is to make sure from step (1) to (4), no finger touching the inside of the mask (keep the mask folded flat).

The mask is intended to be reuse by same person. Parent may help their children to replace the filter without tocuhing the inside of the mask. It is not recommended to be shared by different users.

I have no idea how long the filter will last under what situation, is there a way to calculate that?

CityRider

CityRiderat 08:33

Hi Dr. C,

Do you know if IOM may be interested to evaluate prototype of new design?

anonymous – at 10:01

CityRider, I commend you on your efforts to develop a mask suitable for children. The biggest problem I have is finding a mask for children under the age of 3. Second problem is keeping masks on children. Tried to get my 5-year-old to wear a child’s surgical type mask to doctor, and she wouldn’t keep it on. Like trying to keep a hat on a kid.

A suggestion - consider putting characters, colors, or decorations on the masks to make them attractive to children.

Dr C – at 12:21

I don’t know, go to the IOM website:

 http://www.iom.edu/

And the contact info is on the lower right hand side.

CityRiderat 17:17

anonymous, thanks for your kind words and suggestion. I will certainly take that into consideration. Do you want to test a prototype when it is ready?

CityRiderat 17:40

Dr. C, thanks for the pointer. I notice the workshop was held on 6–7 March http://www.iom.edu/CMS/3740/32033/32544.aspx I will try to get in touch with them.

PirateGrlat 20:46

Hi CityRider,

Thank you for your response to my questions.

Reading your reply has raised a few more questions though.

The idea of using the whole mask as a one-way valve is very interesting, but I am concerned that if the mask lifts away from the face far enough to let air escape from inside the mask, it may also allow room air to be sucked in before the mask has returned to its original position against the skin…to over come this concern, you would need to be able to test the rainbow mask and demonstrate that there is no way for room air to be sucked into the mask around the edges.

A simple way to do this would be to perform a standard NIOSH qualitative mask fit test. In case you are not familiar with this fit test, a person puts on the mask and has a hood placed over their head. The person conducting the fit test then instructs the mask wearer to perform certain motions and exercises designed to test how well the mask keeps its seal during normal activity. As these motions/exercises are being performed, the person conducting the test sprays a testing mist ( a fine mist that can either be tasted or smelled) if the mask seal is good and stays good during the various activities, the mask wearer will go thru the entire test without tasting/smelling the test mist. If at some point during the test, the mask wearer can taste/smell the test mist, this means that room air is able to get into the mask thru small leaks and that the seal is not good. You would have to prove that no outside air leaks in before anyone would be allowed to wear the mask in a hospital or doctor’s office in the U.S.

Have you conducted these types of tests on the Rainbow Mask?

In the U.S. this test is required by law to be performed to prove a good seal can be made with a mask for every person who will wear an N95 mask in a hospital or healthcare setting.

Also, have you tested the plastic you will make the mask from to make sure that it can be disinfected and reused? In the U.S. a reusable mask is generally disinfected with a bleach solution, an ammonia solution or an aqueous solution of iodine. Can the materials you are making the Rainbow Mask from be cleaned repeatedly with these chemicals without damaging or weakening the plastic or the head band?

In order to be considered “reusable”, the mask must be able to be disinfected even if it is only used by one person because if that person is wearing the mask in a hospital or other healthcare situation, you must be able to kill all of the virus and bacteria that may get on any part of the mask before you put the mask away at the end of the day.

Re: the N95 filters, is there any one –way barrier between the filter and the wearer’s breath? Most reusable masks are designed so that exhaled breath never touches the filters which allows those filters to last for up to 12 hours in many cases before needing to be changed. As I mentioned in my previous post, if there is no barrier between the exhaled breath and the filters, then the filters must be changed every 30 to 60 mins due to moisture damage.

You stated in your first post that the Rainbow Mask has N95 filters. But you did not answer my questions about what is the expected service life of these filters? Are they moisture resistant? What is the average time to particle penetration? (most N95 masks start to degrade after 30 to 60 mins use in an infectious environment)What is the average wear time before the filter becomes clogged?

All of these questions can be answered with data that should have been collected when the filter material was tested and awarded an N95 rating. I assume that you did not develop a new N95 filter material but rather are making your filters from an existing N95 material. Who ever makes the N95 material you are using should be able to answer most of these questions for you. The answers are very important to know.

The average wear time before the filter becomes clogged depends a great deal on the size of the filter, how often a person breathes and how much contaminant is in the air. This is why the small filters on your mask concerned me…most N95 masks begin to become clogged in a “normal” non-infectious disease environment after a few hours wear and in most cases, the filter is the size of the entire mask – MUCH more surface area than your filters look to have. Most reusable masks have a filter that is folded many times so that it has even greater surface area than a typical N95 mask does.

Have you had anyone put on the Rainbow Mask and wear it in a dusty environment to see how fast it gets clogged? (a good rule of thumb is the filter is starting to get clogged when the person wearing it notices that it takes a little more effort to breath in thru the filters.)

I am also concerned about the method you describe for replacing the filters…there is simply no way that you can prevent the inside of the mask from being contaminated since as soon as you pull it away from the face, room air will get inside and if you have been in an infectious disease environment such as a sick room, then there is enough virus or bacteria in your clothes, gloves, or just in the air that the inside of the mask must be considered contaminated any time you take it off and must be completely disinfected before new filters are put in. Otherwise, in the case of Bird flu of SARS, you risk breathing in deadly virus that is on the inside of the mask when you put the mask back on.

This is why most N95 masks worn in a hospital that need to be changed often are disposable – meant to be worn for 30 to 60 mins and then thrown away – because it wastes a great deal of time to have to clean and disinfect a mask every 30 to 60 mins.

This is not a problem with most reusable masks because their filters last for up to 12 hours so the mask only needs to be removed and disinfected once per day.

Your ideas about masks sound very interesting, but they need to fit into the established guidelines to make sure that you will be able to sell it to the widest market.

CityRiderat 21:33

PirateGrl,

Again your informative reply is greatly appreciated. To be frank I don’t have answer to most of your questions, especially related to disinfection.

However, the immediate need for me is to develop a practical reusable mask to better protect children outside of hospital (e.g. bus, school). I mean better than surgical mask or cotton mask which are quite popular in some of the Asian countries.

I will certainly work towards what you’ve suggested. Testing the protoypes, including the fitting test you’ve mentioned, should be a part of the next step. I will also check if it is possible to isolate the exhaled breath from the filter.

22 March 2006

CityRiderat 22:48

Dr. C. I received a reply from IOM saying that they are not the authority to evaluate new mask, and they suggest I contact NOISH. I will do so when the product is ready.

So far I receive ONE interested parent to try the prototype mask. I certainly welcome more people to try it. I am at a stage to fine tune the design so that it is more suitable for the end users. Do reply to this thread if you have any suggestion regarding your idea of a “perfect” facemask.

CityRider

26 May 2006

BroncoBillat 00:46

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