Information first made available in April 2020 and revised in May 2020.
This webpage is one portion of the greater exploration entitled "Face Masks: Merging Science & Home Remedies" that can be access at https://clothingtextiles.ualberta.ca/facemasks/.
Bissonnette Eyewear-friendly, Two-layer Mask with Room for a Third Layer
(Click on title above for step-by-step instructions and fit information)
(April 2020)
Edmonton, Alberta
April 11, 2020
Revised May 7, 2020
Dear reader,
You have likely been bombarded by messages regarding the making and use of cloth face masks at home. Like me, you may have wanted to know more about the science behind home remedies offered to the public. As an informed citizen, you may have read information with a critical eye. How do the people interviewed know what they know? Has this been proven or is this a person's opinion? If it is an opinion, is it based on solid scholarly evidence? Misinformation abounds and lives are at risk.
In this May 7, 2020, revised website introduction, I would like to share with you my thoughts on information I have read in peer-reviewed articles, papers waiting for peer review, and in some information presented by governmental agencies, journalists and non-journalists. While peer-reviewed sources were initially my main focus, scientists are getting more reactive during the COVID-19 pandemic because time is of the essence.
When a manuscript is completed (which may take a significant amount of time) and sent for publication, the peer review process may take 9 to 12 months (or more) to account for the peer-review process and the editorial work before an article is accessible online or in print. Many research projects are currently taking place in an accelerated manner. Results may even be made accessible before the peer review process. As a result, peer reviewers and a wider community of scholars vetting the work post publication have had no time to verify, accept (partially or fully) or negate the work. This is how science usually advances with the most valid ideas being pushed further while many other ideas are left behind. I have recently come across an article peer-reviewed in 4 days that had many errors that are bound to affect the authors’ conclusions. The peer-review process is not perfect and many other experiments are occurring outside of it: one must remain vigilant when addressing a wide variety of sources.
What appears to be a simple object, the homemade face mask (HFM), turns out to be quite problematic. As a garment made by individuals who are using materials readily found in their surroundings in designs that, like the materials, have not been tested for their effectiveness in preventing infection, this object varies immensely. The primary use of HFMs is to keep the virus particles emitted by a mask wearer from spreading to others. HFMs are not respirators that aim to prevent the inhalation of virus particles a wearer breathes in, as in the case of N95 masks. As a researcher who deals with textile and dress and as a maker trained as a designer, many questions arose about HFMs that I could not find solid answers for prior to April 2020. I am attempting as best I can to present my quest in these webpages. This is by no means an exhaustive piece of research and it doesn't intend to be a definitive piece on the subject of HFMs. As information comes my way, I may update things as much as I can in the time that I have and this will be reflected on the date and time posted in the heading.
While scholarly information is accessible through sites like Google Scholar, few authors of articles appear to have consulted with textile scientists who do research on Personal Protective Equipment (PPE). This is obvious to someone like me who is not an expert on face masks nor a person trained as a textile scientist. There are many pros and cons to a wide variety of researchers doing their best to try to solve the HFM conundrum. Ideas can come from different perspectives and this can allow for innovative solutions that a person trained in only one field of study may not have considered. Interdisciplinary research requires collaboration, a lot of humility from all participants and an opened mind to solve the problems we are now facing.
One of the most deplorable situation I have found thus far reading more peer-reviewed scientific literature is the lack of understanding or interest on fibres and fabrics and their properties. There is a great deal of knowledge there that is lacking in many otherwise valuable research projects. Many authors will, for instance, talk about fibres and fabrics as one. While cotton is a fibre, it can be used for a variety of fabrics and can come in loosely-woven textiles, such as plain-weave cheese cloth or gauze, to dense twill-woven denim. Not only must fibres (e.g., cotton, wool, silk, polyester, etc.) and weave structures (e.g., plain weave, twill weave, crepe weave, etc.) be identified by researchers but other factors such as thread count matter as well.
Scientists often describe a textile use (i.e., towel, pillow case, scarf, etc.) rather than describing the components that are part of its material composition, structure and possible chemical treatments. Not all scarves or sheets are the same! If research is to advance forward, it much be replicable and simple saying “a high thread count cotton sheet” is insufficient (for our purposes today, the fibre, thread count and weave structure is sought (e.g., 280 thread per inch 100% cotton plain weave)). The information presented in this website aims to address this situation in light of this gap in textile knowledge.
You may have gone online to get answers on how to make a cloth face mask at home and what type of materials to use. Three separate issues have made me weary of the current coverage on these topics. Firstly, the lack of rigorous scientific evidence offered to the general public; secondly, the lack of knowledge of textile products for many scientists; thirdly, the lack of solutions and/or testing for over 4 billion adults who must wear glasses and masks simultaneously. My findings hope to address all of these topics to suggest an improved multiple-use product that can be made at home.
Anne Bissonnette, PhD
Associate Professor, Material Culture and Curatorship
Human Ecology Department
University of Alberta
Curator, Anne Lambert Clothing and Textiles Collection
Harold William Sellers, editor and contributor
TABLE OF CONTENT (click on the main headings for access):
1A. Government of Canada
1B. Government of the United States of America
1C. Explanation of the Minor Differences Seen in the Canadian and American Sites Presented in 1A & 1B
1D. Problems Encountered in the Design and Use of the No-Sew Models Presented in 1A & 1B
2. PEER-REVIEWED SCIENTIFIC INFORMATION (1918-2013: History & Limited Research Scope)
2A. Pros & Cons
2B. Scholarly Findings and their Impact on Cloth Face Masks Making & Use
2C. Bibliography of Works Cited in this Section
3. PEER-REVIEWED SCIENTIFIC INFORMATION (2008-2020: Advanced Testing)
3A. Pros & Cons
3B. Scholarly Findings and their Impact on Cloth Face Masks Making & Use
3C. Surface Coating & Care for Re-use
3D. Bibliography of Works Cited in this Section
THE 10 PRONOUNCEMENTS
|
4. TURNING SCIENCE INTO SOLUTIONS FOR THE PUBLIC GOOD (Solutions for the Making, Use & Care of Homemade Cloth Face Masks Based on Evidence)
4A. Designs
4B. Materials
4C. Putting on and Removing Your Mask & Care for Re-use
Based on the peer-reviewed evidence presented thus far, the following are solutions for the design, making, use, and the care of cloth face mask made at home to help address the COVID-19 pandemic. Not all the scientific evidence is in agreement, which is typical. Some of the peer-reviewed testing is also flawed and leads to further unanswered questions. Further non-peer-reviewed information from credible sources may be added at this point but with the proviso that better information will be incorporated to the website in time. This may change or add to the pattern and the fabric suggestions. The ultimate goal is to draw from multiple sources of credible information available to create evidence-based homemade face masks.
Please note that in no way is this research claiming that a homemade cloth mask can be substituted as effectively for tested N95 masks or other respirators and surgical masks available commercially. The purpose of this research is to use evidence-based, peer-reviewed scientific research as much as possible to address homemade cloth face masks to prevent further infection due to the Novel Coronavirus. I am personally convinced that better solutions are likely to exist than those presented to you today. However, without the evidence, I may mention such solutions but I will only suggest those I can document without too much discomfort.
As the research suggests, homemade cloth face masks should be a component of several measures use concurrently, which include government-sanctioned hygienic practices (such as the washing of hands), social distancing, and other methods available online via governmental websites.
This research was conducted partly to address eyewear use. Following the research, and in addition to experimentation with different face mask designs and cloths, individuals may want to use their eyewear to secure homemade face masks that may not include a wire over the nose. In addition to increasing the fit of the cloth to the face, eyewear may also further detract wearers from touching their eyes. If the wearer does not wear prescription sunglasses, they may want to use sunglasses or safety glasses sold to individuals who work in laboratories or other hazardous work sites or use power tools to work with wood and metal products. These can often be found in hardware stores.
Before and after handling your face mask, you should always wash your hands and have a plastic or paper bag at hand to contain the mask in order to avoid cross-contamination. Treat your mask with utmost caution and always assume it is contaminated. The plastic or paper bag that will receive a worn mask should be considered contaminated as well.
4A. Two or Three Layers Design
The goal the proposed Bissonnette Eyewear-friendly, Two-layer Mask with Room for a Third Layer is to create a good seal between the mask and the face. The most problematic area is the nose and the orbits of the eyes.
The basic design offered here is similar to one presented in the website of the Government of Canada and the United States’ Center for Disease Control (CDC). I doubt that this is the best design as the cloth is very close to the mouth and nose, which creates some discomfort. However it is the better alternative from both of these websites for the following reasons:
- In the second model (“Quick Cut T-shirt Face Covering”), the space between the threads in a knitted textile expands as it is stretched, decreasing its filtration capabilities. Additionally, the model only works on t-shirts with no side seams (which is not made explicit in either websites) and only one layer for the mask is far less effective.
- In the third model (“Bandana Face Covering”), the wearer ends up having to breathe through a total of 18 layers of fabric once the piece of textile is folded. The likelihood of being able to breathe easily through these 18 layers is slim. As the Canadian website adds a coffee filter or also suggest the use of a paper towel in addition to the bandana, this increases the layers beyond the 18 folds in the piece of cotton cloth, thus reducing breathability further.
In the future, I will be monitoring The University of Florida’s Department of Anesthesiology website since researchers have shared two patterns that have been fit tested (albeit not as part of a peer-review process). One of which resembles the prototype presented here. Their prototype #2 may have the ability to bring the material further away from the face but, with a vertical front seam in the lower half of the mask, this may impact the mask’s filtration efficiency. Their masks are made of a medical textile not found commonly at home (Halyard sterilization wrap). The stiffness of this textile may impact the design of prototype #2.
PROPOSED TWO LAYERS MASK CAN BE WORN TWO WAYS:
The mask that was developed is of a type inspired by surgical masks but has modifications. Firstly, it can be worn in two ways:
- FOLD UP
For those who will use the mask with eyewear, the section of the mask that is placed on a fold is made thin enough to fit under eyewear and can thus be placed directly under the eyes. Eyewear may help to create a good seal. The removal of a seam leads to only two layers of cloth rather than four layers (because of seam allowances) and stitching, which is bulky and hard to fit under eyewear. Depending on the wearer’s eyewear, this may be the best solution to create a seal. Some eyewear may accommodate the wearing of the mask with the fold down (see next section). - FOLD DOWN
For those who will use the mask without eyewear, the section of the mask that is not stitched close and thus left with an opening (to insert a third layer) can made with a channel that accommodates a metal wire that will be placed over the nose. This metal wire can be made of a paperclip, garden wire, or any type of wire that retains its shape once bent. Before the insertion of the wire inspect the end for sharp edges. If need be, use pliers to turn the end of both extremities at least 180 degrees to lessen sharp edges.
POSSIBILITY OF THIRD LAYER INSERTION:
A filter can be inserted as a third layer between the two woven layers of cloth. It is recommended that a non-woven material be inserted if the wearer can sustain the added restriction on breathing that this filter creates. This non-woven filter may be most effective to intercept particles smaller than 1000 um. Individuals may also choose to spray this filter or immerse the entire mask with a salt and water solution to create an inhospitable environment for the influenza virus. See below.
4B. Materials
BREATHABILITY
When making a two-layers face mask, test your ability to breathe through the layers of any materials you select to use before you proceed. It has been demonstrated that more layers are not necessarily better. If breathing is too hard through the materials that will filter the air, the air will bypass the mask and come in through other ways (Davies et al., 2013: 417). Additionally, if it is too hard to breathe, you are not likely to use this mask due to over heating or oxygen starvation, which defeats the purpose of making it .First and foremost it must be breathable. Evidence shows any fabric will be a beneficial filter of some nominal quality greater than wearing no mask at all.
RECOMMENDED FIBRE: 100% COTTON FIBRE FOR MASK SECTION THAT TOUCHES THE FACE
Cotton fibres appear to be the most common choice for homemade cloth face masks in the literature. It is recommended that they be washed and dried before the fabric is cut to remove any pre-existing surface treatments. The use of cotton may be due to its breathability. As such, for contact with the face, 100% cotton cloth is best but, for ties, any other type of fibre could work but make sure the fibrer in the ties can withstand harsh laundering. This excludes the use of elastics.
FILTER: USE SAFE, NON-WOVEN CLOTH
Non-woven material may include readily available household items that have been proven not to endanger one's health. This may include paper products like absorbent paper towels for kitchen use (ex. Scott Towels, Bounty,…). Commercial filters for furnaces or vacuum cleaners that may contain fiberglass particles that could be aspirated are not recommended though they are less common now. Filter materials should be permeable and supple enough not to affect proper breathing. While very fine woven textiles may have smaller openings between threads, these openings still create a large sections for extremely small particles that make up 87% of the exhaled breath of influenza-infected patients (Rengasamy, Eimer and Shaffer, 2010: 790). Adding a non-woven filter can provided a different type of filtering material.
WEAVE STRUCTURES OF TEXTILE
Very little information is available in research on the subject. One source indicates that "the filtration capacity improved when the number of threads increased" (Chughtai, Seale, and MacIntyre, 2013: 3). A non-peer-reviewed French source (written by scientists) suggests tightly-woven cloth for two to three layers of same or different fabrics. (AFNOR SPEC S76-001, 27 Mars 2020, 34. https://latelierdesgourdes.fr/wp-content/uploads/2020/03/AFNORSpec-S76-001-MasquesBarrieres-AnnexeC-patrons.pdf). While this French source does not recommend using only one layer of cloth, the issue of breathability must be kept in mind as well as the fact that, if breathing is too hard through multiple layers, the air will bypass the mask and come in through other ways (Davies et al., 2013: 417). As such, I recommend the use of at least one layer of as fine a weave structure as is comfortable for your breathing. 100% cotton textiles sold in high thread count, such as 280 thread per inch or more, are often used for bedding (sheets & pillowcases). Look in your holding and see if you can find a pillowcase that would allow you to breathe well through one or two layers. If you do not have a pillowcase, you may try other household textiles or look online for a high thread count pillowcase. Bedding textiles are a type of textiles where the fibre content must be indicated, as it is a regulated product. When the thread count is high, manufacturers also may include the count number in their advertising, as this is a selling point for their product.
If the wearer has 100% cotton knitted fabric, this has been used in research and proved effective (Davies et al., 2013: 413). This type of textile is often used for T-shirts.
If two layers of a high thread count fabric is hard for you to breathe through but one layer is feasible, consider using the high thread count textile on the interior of the mask and for about 2 cm after the fold. Add a seam allowance after this 2 cm mark and sew a very loosely woven 100% cotton textile for the remainder of the pattern. This loosely woven section will touch the nose and mouth and will prohibit water from deteriorating the third filter layer, which may be a non-woven paper product. Look around for a loosely-woven cotton fabric. This may be a heavily-laundered handkerchief, sheet, or garment. A style of loosely woven, 100% sheer cotton summer garments made in India is often found around universities retail establishments that sell clothing to college-age women.
APPLICATION ON BARE SKIN
For the best seal of the mask on the face, the mask should be placed on bare skin, free of facial hair. As such, individuals with facial hair where the exterior of the mask touches the face should consider a close shave.
LENGTH OF USE
While the current homemade face mask is designed to be reusable, a non-peer-reviewed French source (written by scientists) suggest a maximum wear of non-government-tested, homemade face masks to half a day. (AFNOR SPEC S76-001, 27 Mars 2020, 6. https://latelierdesgourdes.fr/wp-content/uploads/2020/03/AFNORSpec-S76-001-MasquesBarrieres-AnnexeC-patrons.pdf).
4C. Putting on and Removing Your Mask & Care for Re-use
GENERAL
General information is available from the Government of Canada under “How to put on a non-medical mask or face covering” & “How to remove a non-medical mask or face covering” at https://www.canada.ca/en/public-health/services/diseases/2019-novel-coronavirus-infection/prevention-risks/how-put-remove-clean-non-medical-masks-face-coverings.html
PUTTING ON YOUR Bissonnette Eyewear-friendly, Two-layer Mask with Room for a Third Layer
1) Wash your hands.
2) Insert a piece of non-woven textile like an absorbent paper towel in the pocket construction of the clean and dry face mask and, if this works for you with your eyeglasses, the metal wire through the opening at the hem.
3) Remove eyewear by the temples (long horizontal sticks that end behind your ears) and wash your glasses and your hands.
4) Using the ties on the top section, place the mask on your face so that the top centre section rests more than halfway on your nose and the top ties are placed over your ears. Secure the ties loosely at first and put your glasses on. Adjust the mask until you feel comfortable and then secure the top ties more tightly.
5) Secure the bottom ties of the mask below your ears.
6) From this point on do not touch the front of your mask until you are by a place where you can wash your hands and where you can dispose of the mask in an assigned plastic of paper bad so as to avoid cross-contamination. Treat your mask with utmost caution and always assume it is contaminated. The plastic or paper bag that will receive a worn mask should be considered contaminated as well.
N.B: there are two ways to wear the Bissonnette mask with eyewear: please see the end of the document entitled "Bissonnette Eyewear-friendly, Two-layer Mask with Room for a Third Layer" to find one the way that works best for you. You may have to bring the mask further up or down your nose several times until you find something that works. Not all eyeglasses are constructed alike so it is difficult to predict what will work to reduce or eliminate fogging of the lenses.
REMOVING YOUR Bissonnette Eyewear-friendly, Two-layer Mask with Room for a Third Layer
Always assume your mask is contaminated.
1) Place a plastic or paper bag in which to place the mask near the sink.
2) Remove eyewear by the temples (long horizontal sticks that end behind your ears) and wash your hands and your glasses.
3) DO NOT TOUCH THE MAIN PORTION OF THE MASK but remove the bottom ties of the mask first.
4) Remove the top ties of the mask next and, while holding these top ties, place the mask in the plastic or paper bag and remove the metal wire that fits over the nose (if applicable) and seal the bag shut.
5) WASH & DRY YOUR HANDS AND THE WIRE right after handling.
N.B. While there is no evidence that microwaving can kill the influenza virus, those who decide to microwave their mask should be careful as metal pieces can cause fires and the process may not kill the virus load. Microwave ovens do not always heat evenly so cool spots may exist that do not kill the virus load. If a user insists on microwave heating the mask, it may be best to flip the mask around at intervals to spread the heating effect. Alternatively, the mask should be wet and then put into a heatproof container with a lid and 1/4-inch water. With subsequent water heating, the mask will be thoroughly heat treated in 2 or 3 minutes at 100 degrees C. As importantly, please remember to remove any metal parts from the mask such as the nosepiece wire before microwaving to avoid electrical arcing and subsequent charring or fire.
6) WASH the mask.
The mask must be cleaned after each use to remove any saliva or nasal fluid that will have landed on its surfaces. You may want to use detergent and bleach. If no elastics are used in your mask, the bleach will not damage the materials extensively (since bleach harms elastic). Remember metals are incompatible with bleach too, causing rusting or other forms of corrosion. A non-peer-reviewed French source (written by scientists) suggests washing with detergent at 60̊ C for a minimum of 30 minutes (for complete cycle that includes wetting, washing, rincing). (AFNOR SPEC S76-001, 27 Mars 2020, 11. https://latelierdesgourdes.fr/wp-content/uploads/2020/03/AFNORSpec-S76-001-MasquesBarrieres-AnnexeC-patrons.pdf).
5) DRY the mask.
To further mitigate any possibility of the virus surviving, dry the mask well. You may want to put the mask in the dryer after the washing process is completed. If no dryer is available at home, you could dry the mask at 70 degrees C (160 degrees F) in a gently warm oven at the lowest setting or in a heated clothes dryer for 30 minutes. You may chose to dry the mask at room temperature for more than 4 hours in a quiet untraveled place (away from pets and children) indoors or outside with dry circulating air, perhaps extra time overnight in high relative humidity situations. Alternatively hang the mask outdoors in full sunshine to dry. A rich source of solar ultraviolet light, especially at noon in low latitudes, may also help to kill viruses and bacteria in addition to the drying factor simultaneously at work.