CATER Mask Decisions

January 4, 2021

Vaccines are not a Short Term Solution so We Need the Safe Bubble Initiative

New Methods are Needed  to Assure a Tight Fit on Every Mask Worn in Public

Suppliers of Disposable Masks are Focused on Increasing Production and Not Necessarily Holistic Solutions

Important New Findings on Performance Differences Between Masks

N95 Tested at 98% FFE

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Vaccines are not a Short Term Solution so We Need the Safe Bubble Initiative

There are many reasons why we will need to depend on HVAC and masks as part of a Safe Bubble Initiative (SBI) for at least several years.

·         Hundreds of thousands of wealthy citizens of the world will die in the next 12 months without the SBI.

·         Millions of poorer citizens will die in the next 4 years without SBI.

·         Major impact of the vaccines will not be felt in wealthy countries until late in the year and not for years in poorer countries.

·         New variants of the virus are eventually likely to evolve into one which resists the present vaccines.

·         Prevention of future pandemics along with efforts to reduce the impact of air pollution, wildfires, and influenza will provide long lasting benefits.

New Methods are Needed  to Assure a Tight Fit on Every Mask Worn in Public

Mask leakage can vary from 2 to 60%.  The differences in virus transmission  are huge when you include both emitter and recipient. At 2% escaping from the transmitter only 2 x .02 or .04%  of the air leaks into the recipient mask. With the 60% leakage 36%  can be inhaled by the recipient. So 36/04 or 900 times more virus is inhaled with the looser masks.

When you combine air leakage and media efficiency for both transmitter and recipient the same high ratios are found. However, other measures such as limiting capacity are less effective and hugely costly to the economy. You can require a school to operate at 10% capacity but that only provides a 10 to 1  reduction ratio.

With the Safe Bubble Initiative every entrant to a facility would be checked to assure that his mask is tight fitting and efficient. There would be a tiered approach.

·         Tier One: Every mask type and size would be tested by the manufacturer under various motions and with individuals whose facial features match the mask size. Quantitative fit testing would be used. An approved fit testing laboratory would conduct these tests and provide the rating. The entrant to a facility would only have to show that he is wearing a rated mask and has chosen a proper size.

·         Tier One Alternative: Local operators such as Fitness Centers or Department Stores could sell masks and provide fit testing for each purchaser. If they are selling one brand of mask with five sizes, they select the appropriate size for the purchaser and run the two minute fit test. 

·         Tier Two: Each entrant would be checked to see that he has an accredited mask and that it is being worn properly. This inspection could include something as elaborate as periodic qualitative testing or just visual inspection.

One or more visual methods need to be created. A visual check can determine if the mask has the following attributes:

·         Stays in position on face across a variety of motions: walk, talk, bend over, head side to side

·         Does not restrict field of vision

·          Adjustable noseband to seal gaps on either side of nosebridge-mandatory

·          Head strap accessory for alternate attachment with adjustable tension in back of head-optional

·         Trim or other design element to create a seal between user's face and mask-optional

The manufacturer also should supply

·         Correct donning, doffing, and noseband instructions

·         Product support to ensure correct size

·         Offer in several sizes to fit a wide range of facial shapes and structures

·         Practical performance testing on test subjects to determine leakage under normal activities (on sample test subjects in lab setting)

A manual check can also be provided. Here is the procedure recommended by Vogmask.

“Place your fingers on the cheekbones and thumbs on sides of chin to do inhale and exhale fitting check. 

"Inhale slowly. Check to see if the facepiece suctions slightly towards your face. No air should leak in between your face and mask.

1. Exhale slowly. The facepiece should be bulging slightly outwards as exhale exits back through facepiece.
2. Check again for leaks between your face and the facepiece of the respirator.
3. If you detect any leaks, readjust the ear loops or head straps and check again for fit.
4. If you cannot get a good seal around nose and mouth, the mask is not correct size and we request you contact us.”

Additional ways to check the fit could be developed.  Some creativity is needed. Here is one idea.

Instead of lighting up a pumpkin why not use a cheap disposable light to light up the openings in the mask.  the subject would place the light in his mask. He could manipulate it through the soft fabric or with attached threads and change the trajectory of the light beam to check the periphery  while the inspector is watching. Lights for lanterns are 30 cents each on Amazon. So they could be given to the entrant after use.

Variations of qualitative testing could be performed. A test only requires a hood and method of injecting a sweet or bitter aerosol.

Many facilities have  some sort of  a line where temperature is checked.  They could be utilized with a walk through unit. A fan filter unit and walk in module would cost less than $5k.  Each entrant could be tested with a modified taste test.

These are just a few approaches. There could be much better ones if only a little time is spent devising them. When you consider that the mask fit is as important as vaccines and more important than social distancing it is important to measure it and act accordingly.

Suppliers of Disposable Masks are Focused on Increasing Production and Not Necessarily Holistic Solutions

The huge production requirements based on multiple mask use per day for healthcare workers will hamper efforts to supply enough masks and filter media to properly address COVID. Therefore reusable masks are a critical necessity.

3M  replied to the McIlvaine proposed  Safe Bubble Initiative by pointing out that all their resources are needed to make disposable masks for healthcare workers. At the very least there should be an effort to see how many times disposable N95 masks can be worn by the public before the fit and efficiency deteriorate. Many of the two billion masks 3M hopes to make will be needed for  applications where a disposable mask is most appropriate. When a nurse is entering a COVID ICU unit and then may be entering the room of a cancer patient the risk of transmission from one patient to another is too high to consider wearing a previously used and sterilized mask.

But the average individual who has probably not been exposed to COVID during the day can wear his mask multiple times. The N95 mask can have a high net efficiency and even with some deterioration will  be many times more effective than the typical  cloth mask.

The 3M position is understandable. They are to be commended for the great effort they have made to increase production. It may turn out that there really is a need for the two billion masks they make to be used by medical personnel. If four masks are required each day then this is only enough for 500 million mask days or 1.7 million people for 300 days.  Here is the 3M reply.

Thank you for your inquiry. 3M is committed to supporting public health and the government response to the COVID-19 outbreak. While 3M appreciates offers to collaborate, we are unable to commit resources to review your new product idea at this time. Since the outbreak of COVID-19, we have increased our production of personal protective equipment, and we are working to nearly double our production of respirators, to almost 2 billion globally, within the next 12 months. A diversion of resources would reduce our ability to maximize production of critical supplies and therefore reduce our ability to have the greatest public health impact possible.

While we are unable to work together at this time, we may be interested in a potential collaboration in the future when our production schedules are back to normal volume. You are welcome to submit your unsolicited, non-confidential idea at https://www.3m.com/3M/en_US/company-us/unsolicited-idea-submission-policy/. That link will provide guidelines for 3M acceptance of unsolicited ideas. As a reminder, you are free to submit your ideas to other companies.

Thank you for your understanding as we work to deliver high volume production in the short to medium term.  We are grateful for your commitment to public safety during the rapidly changing COVID-19 outbreak and are amazed by the number of people and companies willing to come together to help protect our healthcare workers on the front lines of this fight.

Important New Findings on Performance Differences Between Masks

A new study for CDC confirms many past studies. Tight fitting and efficient masks  perform much better than the average public mask. An abstract and summary is provided below along with a link to the full article.  The article provides

Evaluation of Cloth Masks and Modified Procedure Masks as Personal Protective Equipment for the Public During the COVID-19 Pandemic

Phillip W. Clapp, PhD^1,2; Emily E. Sickbert-Bennett, PhD, MS³; James M. Samet, PhD, MPH⁴; et alJon Berntsen, PhD⁵; Kirby L. Zeman, PhD²; Deverick J. Anderson, MD, MPH⁶; David J. Weber, MD, MPH^3,7; William D. Bennett, PhD^2,7; for the US Centers for Disease Control and Prevention Epicenters Program

Key Points

Question: What are the fitted filtration efficiencies (FFEs) of consumer-grade masks, improvised face coverings, and modified procedure masks commonly used during the coronavirus disease 2019 (COVID-19) pandemic?

Findings:  In this comparative study of face covering FFEs, we observed that consumer-grade masks and improvised face coverings varied widely, ranging from 26.5% to 79.0% FFE. Modifications intended to enhance the fit of medical procedure masks improved FFE measurements from 38.5% (unmodified mask) to as much as 80.2%.

Meaning: Simple modifications can improve the fit and filtration efficiency of medical procedure masks; however, the practical effectiveness of consumer-grade masks available to the public is, in many cases, comparable with or better than their non-N95 respirator medical mask counterparts.

Abstract

Importance: During the coronavirus disease 2019 (COVID-19) pandemic, the general public has been advised to wear masks or improvised face coverings to limit transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, there has been considerable confusion and disagreement regarding the degree to which masks protect the wearer from airborne particles.

Objectives: To evaluate the fitted filtration efficiency (FFE) of various consumer-grade and improvised face masks, as well as several popular modifications of medical procedure masks that are intended to improve mask fit or comfort.

Design, Setting, and Participants: For this study conducted in a research laboratory between June and August 2020, 7 consumer-grade masks and 5 medical procedure mask modifications were fitted on an adult male volunteer, and FFE measurements were collected during a series of repeated movements of the torso, head, and facial muscles as outlined by the US Occupational Safety and Health Administration Quantitative Fit Testing Protocol. The consumer-grade masks tested included (1) a 2-layer woven nylon mask with ear loops that was tested with an optional aluminum nose bridge and nonwoven filter insert in place, (2) a cotton bandana folded diagonally once (i.e., “bandit” style) or in a (3) multilayer rectangle according to the instructions presented by the US Surgeon General, (4) a single-layer woven polyester/nylon mask with ties, (5) a nonwoven polypropylene mask with fixed ear loops, (6) a single-layer woven polyester gaiter/neck cover balaclava bandana, and (7) a 3-layer woven cotton mask with ear loops. Medical procedure mask modifications included (1) tying the mask’s ear loops and tucking in the side pleats, (2) fastening ear loops behind the head with 3-dimensional–printed ear guards, (3) fastening ear loops behind the head with a claw-type hair clip, (4) enhancing the mask/face seal with rubber bands over the mask, and (5) enhancing the mask/face seal with a band of nylon hosiery over the fitted mask.

Main Outcomes and Measures: The primary study outcome was the measured FFE of common consumer-grade and improvised face masks, as well as several popular modifications of medical procedure masks.

Results:  The mean (SD) FFE of consumer grade masks tested on 1 adult male with no beard ranged from 79.0% (4.3%) to 26.5% (10.5%), with the 2-layer woven nylon mask having the highest FFE. Unmodified medical procedure masks with ear loops had a mean (SD) FFE of 38.5% (11.2%). All modifications evaluated in this study increased procedure mask FFE (range [SD], 60.3% [11.1%] to 80.2% [3.1%]), with a nylon hosiery sleeve placed over the procedure mask producing the greatest improvement.

Conclusions and Relevance:  While modifications to improve medical procedure mask fit can enhance the filtering capability and reduce inhalation of airborne particles, this study demonstrates that the FFEs of consumer-grade masks available to the public are, in many cases, nearly equivalent to or better than their non-N95 respirator medical mask counterparts.

Introduction

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), is a transmissible virus that infects the upper and lower respiratory tract, leading to a high viral titer in saliva and respiratory secretions. A key public health control strategy for mitigating SARS-CoV-2 transmission is use of masks or face coverings by the public. Masks that completely cover the nose and mouth are effective at reducing seasonal coronavirus and influenza transmission when worn by infected persons and noninfected persons who may come into contact with infected individuals. This is supported by emerging epidemiologic data that indicate that community-wide use of masks can effectively contribute to the prevention of SARS-CoV-2 transmission.

As the adoption of face coverings during the COVID-19 pandemic becomes commonplace, there has been a rapid expansion in the public use of commercial, homemade, and improvised masks that vary considerably in design, material, and construction. Similarly, the press and social media outlets have reported on numerous innovative “hacks,” devices, and modifications (enhancements) that claim to improve the performance characteristics of conventional masks (typically surgical or procedure masks). Despite their widespread dissemination and use during the pandemic, there have been few evaluations of the efficiency of these face coverings or mask enhancements at filtering airborne particles. In this study, we used a recently described methodological approach based on the Occupational Safety and Health Administration (OSHA) Fit Test to determine the fitted filtration efficiency (FFE) of various consumer-grade and improvised face masks, as well as several popular modifications of medical procedure masks.

Methods

Testing Procedure

Fitted filtration efficiency tests were conducted between June and August 2020 in a custom-built exposure chamber (US Environmental Protection Agency Human Studies Facility in Chapel Hill, North Carolina) as recently described. The institutional review board at the University of North Carolina at Chapel Hill waived the need for study approval as well as individual consent needed for device testing. Briefly, a TSI 8026 Particle Generator was used to supplement the chamber with sodium chloride (NaCl) particles that had a count median diameter of 0.05 μm (range, 0.02-0.60 μm) as measured by a scanning mobility particle sizer. The test atmosphere was allowed to stabilize for 30 minutes before FFE testing. The chamber temperature and humidity during testing ranged from 73.4 °F to 85.1 °C and 10% to 50%, respectively. The test atmosphere used for this study reflects typical indoor conditions, with exposure to small particles that are slightly smaller than individual SARS-CoV-2 virions (reported to range between 0.06 μm and 0.14 μm). A sampling port was installed in each mask using a TSI model 8025-N95 Fit Test Probe Kit to allow sampling behind the mask. All masks were fitted on a man (weight, 165.3 lb; height, 5 ft and 10.1 in; head size, 23.0 in) with no beard. A pair of TSI 3775 Condensation Particle Counters were run in single-particle analysis mode to continuously monitor ambient particles (0.02 μm-3 μm) in the chamber just outside the face mask and particles in the breathing space behind the face mask at a sampling rate of 1 second.

Fitted filtration efficiency measurements were collected during a series of repeated movements of the torso, head, and facial muscles as outlined by the OSHA Quantitative Fit Testing Protocol (Modified Ambient Aerosol CNC Quantitative Fit Testing Protocol For Filtering Facepiece Table A–2—RESPIRATORS). The FFE corresponds to the concentration of particles behind the mask expressed as a percentage of the particle concentration in the chamber air and was measured for the duration of each test described in the OSHA protocol (bending at the waist, reading aloud, looking left and right, and looking up and down). The overall percentage of FFE is calculated as 100 × (1 − behind the mask particle concentration / ambient particle concentration), and the percentage of FFE and the standard deviation were calculated across the length of the test. The total testing time for each mask was approximately 3 minutes.

Products Tested

Two categories of products were tested for this study: consumer-grade face masks and medical procedure masks with and without enhancements. The following consumer-grade masks were tested: (1) a 2-layer woven nylon mask (54% recycled nylon, 43% nylon, 3% spandex) with ear loops (Easy Masks LLC) tested with an optional aluminum nose bridge and nonwoven filter insert in place, (2) a cotton bandana folded diagonally once “bandit” style or in a multilayer rectangle according to the instructions presented by the US Surgeon General  https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/how-to-make-cloth-face-covering.html), (3) a single-layer woven polyester/nylon mask (80% polyester, 17% nylon, 3% spandex) with ties (Renfro Corporation) (4) a nonwoven polypropylene mask with fixed ear loops (Red Devil Inc), (5) a single-layer woven gaiter/neck cover balaclava bandana (92% polyester and 8% spandex; MPUSA LLC), and (6) a 3-layer woven cotton mask (100% cotton) with ear loops (Hanesbrands Inc).

The baseline FFE of unmodified medical procedure masks with elastic ear loops (Cardinal Health Inc) was measured (n = 4) and compared with the FFE of the same type of mask with various modifications designed to enhance its function. The following modifications were tested: (1) enhancing the mask/face seal by tying the ear loops and tucking in the side pleats;  https://youtu.be/UANi8Cc71A0), (2) fastening ear loops behind the head with 3-dimensional–printed ear guards; https://www.thingiverse.com/thing:4249113), (3) fastening ear loops behind the head with a 23-mm claw-type hair clip, (4) enhancing the mask/face seal by placing a ring of 3 ganged rubber bands over the mask, with the center rubber band placed over the nose and chin of the participant and the left and right side bands looped over each ear; “fix-the-mask” 3–rubber band method https://www.youtube.com/watch?v=CVjGCPfRwUo), and (5) enhancing the mask/face seal by sliding a 10-inch segment of nylon hosiery over the fitted mask.

Results

This study evaluated the FFE of 7 consumer-grade masks and five procedure mask modifications. The mean (SD) FFE of consumer-grade face masks tested in this study ranged from 79.0% (4.3%) to 26.5% (10.5%), with the washed, 2-layer woven nylon mask having the highest FFE and the 3-layer woven cotton mask having the lowest. The cotton bandana folded into a multilayer rectangle affixed to the ears with rubber bands, as described by the US Surgeon General, provided a mean (SD) FFE of 49.9% (5.8%). Folding the bandana bandit style produced a similar result (mean [SD] FFE, 49.0% [6.2%]). The tested mean (SD) FFE of the single-layer woven polyester gaiter/neck cover balaclava bandana was 37.8% (5.2%). The single-layer woven polyester/nylon mask, which is attached with tie strings, tested at a mean (SD) FFE of 39.3% (7.2%). The nonwoven polypropylene mask with nonelastic (fixed) ear loops tested at a mean (SD) FFE of 28.6% (13.9%).

As expected based on data from our previous work, a National Institute for Occupational Safety and Health–approved 3M 9210 N95 respirator used as a reference control provided very high mean FFE (98.4% [0.5%]; n = 1). The medical procedure masks with elastic ear loops tested in this study had a mean (SD) FFE of 38.5% (11.2%), (which was lower than that of medical surgical masks with tie strings (71.5% [5.5%]; n = 4). Tying the ear loops and tucking in the corners of the procedure mask to minimize gaps in the sides of the mask increased the mean (SD) FFE to 60.3% (11.1%). The “fix-the-mask” 3–rubber band modification and the nylon hosiery sleeve modifications, which were also intended to reduce gaps between the mask and the wearer’s face, improved mean (SD) FFE to 78.2% (3.3%) and 80.2% (3.1%), respectively.

Modifications to improve the seal of the mask against the face by increasing the tension of the ear loops also improved FFE. Attaching the ear loops to the ear guards device using the center hooks (tightest option) increased procedure mask mean (SD) FFE to 61.7% (6.5%). Similarly, joining the ear loops behind the wearer’s head using a claw-style hair clip increased the procedure mask mean (SD) FFE to 64.8% (5.1%). None of the modifications tested enhanced procedure mask FFE to the level of an N95 respirator.

Discussion

In this study, consumer-grade masks and medical procedure mask modifications were tested as personal protective equipment (protection for the wearer) against a test aerosol of 0.05-μm NaCl particles. Although the FFE of consumer-grade masks and face coverings was variable, the FFE of some consumer-grade products exceeded that of medical-grade procedure masks. For example, the 2-layer woven nylon mask with ear loops was tested under various conditions, including with and without an aluminum nose bridge, with and without a commercially available nonwoven insert, and after 1 wash cycle in a standard household washing machine (air-dried on a drying rack). The unwashed nylon mask without a nose bridge or insert had an FFE of 44.7%. The addition of a nose bridge reduced visible gaps around the nose and increased FFE to 56.3%. Adding a nonwoven filter insert to the mask with the nose bridge in place resulted in a further increase in FFE to 74.4%. Interestingly, the FFE of the nylon mask (with the nose bridge but without the filter insert) improved slightly to 79.0% after washing. It is unclear why washing alone improved the FFE from 56.3% to 79.0%. It may be that the washing/drying process unraveled some of the fibers to increase the overall filtration surface, and thus filtration efficiency, of the medium, or perhaps it modified the mask shape or size in a way that improved fit, or both. The washing/drying test was not repeated with additional nylon masks. Further investigation to assess the association of single and multiple washing with mask integrity and material disposition would be necessary to validate any improvement in FFE.

The woven cotton mask, which comprises 3 layers and has a thin, flexible metal nose bridge, had the lowest FFE in this study (26.5%). The relatively loose weave of the cotton layers, while providing improved breathability and comfort, may reduce filtration efficiency. Additionally, we evaluated the FFE of improvised face coverings, including a standard cotton bandana and a neck gaiter balaclava bandana. The cotton bandana, when folded either bandit style or according to the US Surgeon General’s instructions, achieved approximately 50% FFE, which is better than the ear loop procedure mask we tested. Neck gaiter balaclava bandanas have also emerged as a popular face covering, particularly among athletes and young adults. As tested in this study, the single-layer gaiter, which was made of 92% polyester and 8% spandex and fits tightly to the wearer’s nose and mouth, had an FFE of 37.8%. While this face covering appeared to fit the wearer well, with no visible gaps in the seal, it may be that the relatively low FFE can be attributed to the low filtering efficiency of a single thin layer of woven material with large porosity.

For medical procedure masks, modifications that enhanced the fit between the mask and the wearer’s face improved FFE. Simply tying the ear loops and tucking the corners of the mask against the wearer’s cheeks visibly improved mask fit and increased FFE from 38.5% to 60.3%. The most effective modification tested was the use of a nylon hosiery sleeve placed over the procedure mask. This modification, which held the mask tight to the wearer’s face, eliminated all visible gaps and increased FFE from 38.5% to 80.2%. However, donning the nylon sleeve over the procedure mask was cumbersome and limited the wearer’s ability to adjust the procedure mask. Generally, improvements in procedure mask FFE appeared to be associated with the integrity of the seal of the edges of the mask to the wearer’s face, demonstrating the importance of mask fit to maximizing filtration. While all of the modifications described enhanced protection against airborne particles for the wearer, not all were comfortable or practical for extended use. For example, the 3–rubber band “fix-the-mask” modification created considerable pressure on the wearer’s ears, making it uncomfortable after only minutes of wear and raising questions about its adoption by the general public. While the modifications shown in this article can improve mask fit and provide increased filtration of airborne particles, it is important to choose a modification in which discomfort is not a deterrent from wearing the mask for prolonged periods.

The full text is included in the link below to an article in the Journal of the American Medical Association.

Evaluation of Cloth Masks and Modified Procedure Masks as Personal Protective Equipment for the Public During the COVID-19 Pandemic | Infectious Diseases | JAMA Internal Medicine | JAMA Network

N95 Tested at 98% FFE

3M™  says its Aura™ Series Particulate Respirator 9210+, N95 is a breakthrough in comfort and convenience. This three-panel, flat-fold disposable respirator with its innovative design helps provide comfortable, reliable worker protection against non-oil based particles.

The lightweight, three-panel designed disposable N95 particulate respirator helps provide quality, reliable, and convenient worker respiratory protection. 3M uses a variety of innovative technologies and features to help meet respiratory protection and comfort needs. 3M`s proprietary filter media, 3M™ Advanced Electret Media, filters dust and other particles, while allowing for easy breathing. The soft inner material provides added comfort while the soft nose foam and adjustable nose clip help provide a custom seal. Braided headbands provide comfort and help minimize pulling of hair.

Unique features to the Aura™ Series Particulate Respirators include sculpted nose panel that follows the contours of the nose allowing more room for eyewear, embossed top panel that is designed to help reduce the fogging of eyewear from warm, moist exhaled air, and innovative chin tab designed for ease of positioning, donning, and adjustment. These features are designed to enhance user comfort and help increase wearability. The unique three-panel flat fold design is collapse resistant and its individual packaging allows for easy storage prior to use. Suggested applications: Grinding, Sanding, Sweeping, Bagging and other dusty or arid operations. Can also be used to help reduce inhalation of certain airborne biological particles like mold, Bacillus anthracis, Mycobacterium tuberculosis, etc. Example applications include emergency or pandemic preparedness planning, stockpiling, etc.