Author Topic: Of Masks and Man  (Read 54 times)

Chandrasekhi

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Of Masks and Man
« on: October 03, 2020, 04:07:17 pm »
The latest research and information on the effectiveness of different types of masks on SARS-COV2 transmission.

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Chandrasekhi

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Re: Of Masks and Man
« Reply #1 on: October 13, 2020, 07:51:06 am »
Article Publication Date: 02 September 2020

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https://advances.sciencemag.org/content/6/36/eabd3083
Low-cost measurement of face mask efficacy for filtering expelled droplets during speech
Abstract
Mandates for mask use in public during the recent coronavirus disease 2019 (COVID-19) pandemic, worsened by global shortage of commercial supplies, have led to widespread use of homemade masks and mask alternatives. It is assumed that wearing such masks reduces the likelihood for an infected person to spread the disease, but many of these mask designs have not been tested in practice. We have demonstrated a simple optical measurement method to evaluate the efficacy of masks to reduce the transmission of respiratory droplets during regular speech. In proof-of-principle studies, we compared a variety of commonly available mask types and observed that some mask types approach the performance of standard surgical masks, while some mask alternatives, such as neck gaiters or bandanas, offer very little protection. Our measurement setup is inexpensive and can be built and operated by nonexperts, allowing for rapid evaluation of mask performance during speech, sneezing, or coughing.
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Results:
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The paper is referenced in NYPOST:
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https://nypost.com/2020/08/11/duke-university-face-mask-researchers-share-more-on-study/

The best
Medical N95 mask: “3M 1860 Surgical Mask and Particulate Respirator”


The Rest in order of decreasing effectiveness:

1. Surgical mask

This disposable surgical mask was the second-most effective variety, ranging from zero to 0.1 in terms of the particles spread from speaking while wearing one.


2. Polypropylene and cotton
The synthetic material polypropylene, laid in between two layers of cotton, was the third-best.


3. Polypropylene apron mask
This mask made with two layers of the synthetic material was just marginally worse than the one made with both cotton and polypropylene.


4. Cotton mask with ties
The next six cotton masks all performed around the same level, which Fischer said shows variables matter. “It depends how loud you speak, and how well it fits around your face,” or if facial hair causes a looser fit, he said.


5. Two-layer cotton with ties
Right behind the green tie mask was another cotton version with two layers, and straps that went across the bottom and tied behind the ears.


6. Valved N95
N95 masks with exhalation valves are designed to protect the user from breathing in harmful materials, not necessarily the other way around, which could have contributed to their performance.


7. Hand-sewn cotton
This cotton mask was sewn using the popular “Olson” pattern, which is available online.


8. ‘MAXIMA AT’ mask
A pleated cotton variety from North Carolina-based company Hudson’s Hill was essentially tied with the similar-looking single-layer cotton mask below.


9. Single-layer cotton
This one-layer mask performed better than one with two layers, which should serve as a reminder of the variables in the experiment and in life, said Fisher.


10. Pleated two-layer cotton
This two-layer cotton pleated mask performed just slightly worse than other similar styles.


11. Knitted
A mask made from what appears to be a T-shirt knit (Fisher was keen to point out the researchers are not textile experts) had more variability in droplet projection than other styles.


12. Bandanna
...it’s basically useless, multiple studies — including Duke’s — have found.[/b]


13. The worst: Neck gaiter
The stretchy gaiter tested here (a style beloved by runners) was worse than forgoing a mask completely, and was shown to break larger particles into smaller ones, allowing them to slip out of the sides more easily.

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« Last Edit: October 13, 2020, 07:55:58 am by Chandrasekhi »

Chandrasekhi

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Re: Of Masks and Man
« Reply #2 on: October 13, 2020, 08:06:41 am »
Article Published: : Oct 12, 2020
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https://examine.com/topics/coronavirus-masks/
Coronavirus masks: What’s the latest evidence?
We analyzed over 80 studies to help answer your mask questions: efficacy of different types, storage, downsides, and more.

Masks are most efficacious when worn by the infected, but some of them can also help when worn by the healthy. Home mask disinfection may be dangerous if done wrong, but there’s some evidence developing for disinfection in a clinical setting.

...................
What are the different types of masks?
    There are three major types of masks:  -  non-medical, medical/surgical, and N95. In this article, we’ll be covering a variety of studies on all three, from randomized     trials to case reports.
Here’s a simplistic summary of the evidence. Read on for more details.

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« Last Edit: October 13, 2020, 08:09:23 am by Chandrasekhi »

Chandrasekhi

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Re: Of Masks and Man
« Reply #3 on: October 13, 2020, 08:22:27 am »
Publication Date: 26 JUNE 2020
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https://royalsociety.org/-/media/policy/projects/set-c/set-c-facemasks.pdf
Face masks and coverings for the general public: Behavioural knowledge, effectiveness of cloth coverings and public messaging
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SUMMARY KEY POINTS
• Cloth face coverings are effective in reducing source virus transmission, i.e., outward protection of others, when they are of optimal material and construction (high grade cotton, hybrid and multilayer) and fitted correctly and for source protection of the wearer.
• Socio-behavioural factors are vital to understanding public adherence to wearing face masks and coverings, including public understanding of virus transmission, risk perception, trust, altruism, individual traits, perceived barriers.
• Face masks and coverings cannot be seen in isolation but are part of ‘policy packages’ and it is imperative to review interrelated non-pharmaceutical interventions in tandem including hand hygiene, sanitizers and social distancing when maintaining the 2 metre or 1 metre+ distancing rule is not possible.
• Consistent and effective public messaging is vital to public adherence of wearing face masks and coverings. Conflicting policy advice generates confusion and lack of compliance. Populations without a previous history of mask wearing have rapidly adopted face coverings during the COVID-19 period.
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Optimal cloth face coverings are made from specific material (e.g., high grade cotton), hybrid and multilayer constructions (e.g., silk-cotton) and need to be fitted correctly
« Last Edit: October 13, 2020, 08:26:08 am by Chandrasekhi »

Chandrasekhi

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Re: Of Masks and Man
« Reply #4 on: October 13, 2020, 08:38:18 am »
Mask Standards Unmasked. PART 1
Publication Date: 15 March 2020
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https://smartairfilters.com/en/blog/comparison-mask-standards-rating-effectiveness/
Comparison of Mask Standards, Ratings, and Filtration Effectiveness
...

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Mask Standards and Effectiveness Bottom Line
    - Single use masks (normally one layer, very thin) are typically only effective at capturing larger dust particles, but can do so fairly well.
    - Surgical mask standards have higher requirements for capturing virus-sized (0.1 micron) particles, however they vary by region.
    - Pollution masks (respirators) typically capture >90% of virus-sized particles. You can use the rating system in the table above to see the exact proportion each certification requires. This includes ratings such as N95, KN95, FFP1, FFP2 and FFP3.
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Mask Standards Vary by Country
Each country has their own certification standard for each mask type. For example, Europe uses the EN 14683 standard for surgical masks, whereas China uses the YY 0469 standard. Each standard varies a little by country, however they are broadly similar. For respirator masks, China uses the KN standard (e.g. KN95) and the US uses the N standard (e.g. N95).

Read more: what’s the difference between KN95 and N95 masks
...


« Last Edit: October 13, 2020, 09:10:12 am by Chandrasekhi »

Chandrasekhi

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Re: Of Masks and Man
« Reply #5 on: October 13, 2020, 08:45:14 am »
Poor Man's Fabric Test
https://smartairfilters.com/en/blog/best-materials-make-diy-masks-virus/?rel=1
How to Find the Best Material: The Poor Man’s Fabric Test

One problem for using this data at home is that materials like T-shirts and bed sheets are different. Some are thicker; some are thinner. How can you be sure the material in your home will perform similar to the ones we tested?

Without a $3,000 laser particle counter, here’s one handy way to estimate this: try your own “Poor Man’s Fabric Test.”
    - Hold your material up to the light.
    - See how much light passes through it.
    - Compare it to this rubric to estimate the effectiveness of your material.



Chandrasekhi

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Re: Of Masks and Man
« Reply #6 on: October 13, 2020, 08:49:35 am »
 Publication Date: 2020-03-08
Quote
https://smartairfilters.com/en/blog/best-materials-make-diy-masks-virus/?rel=1
Homemade Masks vs. Viruses
Can homemade masks capture smaller virus particles? To answer this question, the scientists tested 0.02 micron Bacteriophage MS2 particles (much smaller – a fifth the size of – COVID-19).

...
On average, the homemade masks captured 7% fewer virus particles than the larger bacteria particles. However, all of the homemade materials managed to capture 50% of virus particles or more (with the exception of the scarf at 49%).
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Chandrasekhi

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Re: Of Masks and Man
« Reply #8 on: October 13, 2020, 09:08:37 am »
https://smartairfilters.com/en/blog/best-diy-coronavirus-homemade-mask-material-covid/
Breathability and Filtration: The Best Combos for Homemade Masks
Bottom Line: The Best Materials for Homemade Face Masks

Based on a combination of breathability and filtration effectiveness, the best materials for homemade masks are:

    Denim (10oz)
    Bed sheets (80-120 thread)
    Paper towel
    Canvas (0.4-0.5mm thick)
    Shop towels

Chandrasekhi

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Re: Of Masks and Man
« Reply #9 on: October 13, 2020, 09:15:24 am »
Mask Standards Unmasked. PART 2
Quote
https://www.nipissingu.ca/sites/default/files/2019-06/Disposable%20Face%20Mask%20Ratings%20Explained.pdf
DISPOSABLE FACE MASKRATINGS: N95, P2, BFE, CE.
What does NIOSH Approved mean?The N95 surgical face mask has been recommended by USA experts as the best protection from SARS. The mask has a >99% BFE (Bacterial Filtration Efficiency). The N95 is the USA equivalent of the EuropeanP2 and P3 masks with the P3 offering the higher protection. The N95 mask has a Particle Filtration Efficiency (PFE) of >95% @ 0.3 micron. Masks are intended for use in infection control practices.
...
The N95 surgical face mask has been recommended by USA experts as the best protection from SARS. The mask has a >99% BFE (Bacterial Filtration Efficiency). The N95 is the USA equivalent of the EuropeanP2 and P3 masks with the P3 offering the higher protection. The N95 mask has a Particle Filtration Efficiency (PFE) of >95% @ 0.3 micron. Masks are intended for use in infection control practices.The P1 disposable dust respirators are suitable for protection against mechanically generated particles to 1 micron, such as dust and mist. Uses include: sawing, drilling, woodworking, sanding grinding andgardening.Standard Tie On and Ear loop Face Masks are the typical disposable face mask which is latex free, hypoallergenic, fiberglass free, fluid resistant and has a three ply construction. These face masks minimize patient contamination to exhaled microorganisms. Offers a >99% Bacterial Filtration Efficiency (BFE).
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Chandrasekhi

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Re: Of Masks and Man
« Reply #10 on: October 13, 2020, 09:36:54 am »
Homemade Mask Guidelines
https://www.npr.org/sections/goatsandsoda/2020/07/01/880621610/a-users-guide-to-masks-what-s-best-at-protecting-others-and-yourself
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Fabric Masks
1. First, consider the fabric itself.
The tightness of the weave is really important. That's the first thing I would ask people to look into," says Supratik Guha, a professor of molecular engineering at the University of Chicago. To check your fabric, hold it up to a light: If you can easily see the outline of the individual fibers, it's not going to make a great filter.
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Researchers say a tight-weave 100% cotton is a good bet. That's because at the microscopic level, the natural fibers in cotton tend to have more three-dimensional structure than synthetic fibers, which are smoother, says Christopher Zangmeister, a researcher at the National Institute of Standards and Technology. That 3D structure can create more roadblocks that can stop an incoming particle, he explains.
...........
2. Think multiple layers
 Several studies have found that masks made of multiple layers are more effective at blocking small particles.

A good option: a mask made of two layers of a tight-weave fabric with a built-in pocket where you can place a filter, says May Chu, an epidemiologist at the Colorado School of Public Health who co-authored a paper published on June 2 in Nano Letters on the filtration efficiency of household mask materials.
What You Need To Know About Protective Face Masks
Life Kit
What You Need To Know About Protective Face Masks

The best bet for the material to slip in as a filter is polypropylene, which is derived from plastic, says Chu.

...............
Chu says polypropylene is great as a physical filter but has another benefit: It holds an electrostatic charge. In other words, it uses the power of static electricity. Think of the static cling that can happen when you rub two pieces of fabric together, says Chu. That's basically what's happening with this fabric: That "cling" effect traps incoming — and outgoing — droplets. "That's what you want — the cling is what's important," Chu says.

And unlike other materials, polypropylene keeps its electrostatic charge in the humidity created when you breathe out, says Yi Cui, a professor of materials science and engineering at Stanford University who co-authored the Nano Letters study with Chu.
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Cui and Chu note that polypropylene will lose its electrostatic charge when you wash it, but you can recharge it by ironing it or by rubbing it with a plastic glove for around 20 seconds.

Once you've got static cling, ka-ching — you're back in business. Cui says a two-layer tight-weave cotton mask alone can filter out about 35% of small particles. But adding a filter made out of two layers of charged polypropylene could boost that filtration efficiency by as much as another 35%, Cui says. You still want a cotton layer closest to your face, he says, because it's a more comfortable material.

If you can't get your hands on polypropylene fabric, reach for tissues: Take two sheets of facial tissue, fold them over and put them inside your mask's pocket so that you end up with a four-layer filter that you can change out daily. "Surprisingly, the four layers of paper gives you adequate protection," says Chu — though tissues don't have the added power of electrostatic charge.

3. Shape also matters:
 mask's ability to filter out particles depends on not just what it's made out of but how well it seals to your face. When it comes to cloth masks, those that cup tightly to your face are best, Cui says. Masks with pleats or folds are also a good choice: The folds expand so that you have more air flowing through the fabric itself instead of leaking out through gaps at the sides of the mask. Masks with a flat front design are less effective, he says.
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Another trick to improve the seal of your mask: Add a layer of pantyhose. Cut a length of hose about 8 to 10 inches long, from top to bottom, from one leg on a pair of hose, and pull it on top of your mask. This forces particles that might have otherwise gone around the loose edges of the mask and been inhaled to instead go through the mask, which can filter them out, says Loretta Fernandez, a researcher at Northeastern University.

Chandrasekhi

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Re: Of Masks and Man
« Reply #11 on: October 13, 2020, 09:41:18 am »
https://www.ddgroup.com/news/ppe-understanding-different-types-of-masks/

Masks Vs Respirators - What's the difference?



Respirator standards: FFP3 vs FFP2 vs N95
Europe uses two different standards. The “filtering face piece” score (FFP) comes from EN standard 149:2001. Then EN 143 standard covers the P1/P2/P3 ratings, which refers to the filtering efficiency.In contrast, the American standard managed by the National Institute for Occupational Safety and Health (NIOSH), uses a “Negativity” score denoted by the letter “N” to refer to filtering efficiency.


Chandrasekhi

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Re: Of Masks and Man
« Reply #12 on: October 13, 2020, 10:12:55 am »
https://pubs.acs.org/doi/pdf/10.1021/acsnano.0c05025
Quote
ABSTRACT:
ABSTRACT:Filtration efficiency (FE), differential pressure(ΔP), quality factor (QF), and construction parameters weremeasured for 32 cloth materials (14 cotton, 1 wool, 9 synthetic,4 synthetic blends, and 4 synthetic/cotton blends) used in clothmasks intended for protection from the SARS-CoV-2 virus(diameter 100±10 nm). Seven polypropylene-basedfiberfiltermaterials were also measured including surgical masks and N95respirators. Additional measurements were performed on bothmultilayered and mixed-material samples of natural, synthetic,or natural-synthetic blends to mimic cloth mask constructionmethods. Materials were microimaged and tested against sizeselected NaCl aerosol with particle mobility diameters between50 and 825 nm. Three of the topfive best performing sampleswere woven 100% cotton with high to moderate yarn counts, and the other two were woven synthetics of moderate yarncounts. In contrast to recently published studies, samples utilizing mixed materials did not exhibit a significant difference inthe measuredFEwhen compared to the product of the individualFEfor the components. TheFEandΔPincreasedmonotonically with the number of cloth layers for a lightweightflannel, suggesting that multilayered cloth masks may offerincreased protection from nanometer-sized aerosol with a maximumFEdictated by breathability (i.e.,ΔP).

Filtration Efficiencies of Nanoscale Aerosol byCloth Mask Materials Used to Slow the Spreadof SARS-CoV‑2
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Electrostatic deposition, occurring due to a charge difference between a fiber and a particle, can also be important in some material
Collectively, the sum of these efficiencies, diffusion (ED), interception (ER), impaction (EI), and electrostatic deposition (EB), yield the

Single fiber efficiency (EF=ED+ER+EI+EB).

Chandrasekhi

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Re: Of Masks and Man
« Reply #13 on: October 13, 2020, 10:40:37 am »
https://www.usatoday.com/in-depth/news/2020/04/27/how-clean-care-for-store-and-reuse-masks-protect-coronavirus-n-95-elastometric-homemade-covid-19/5148025002/
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Cotton mask or neck gaiter? Check out how effective different kinds of masks are
Highlights:
1. Testing the effectiveness of coronavirus masks
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While working on another recently published study, researchers from Duke University evaluated the effectiveness of 14 different types of masks by estimating how many droplets traveled through the mask during normal speech.
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A neck gaiter, an item beloved by runners, ranked worse than no mask at all. The porous fabric may break the larger particles into smaller ones. Smaller particles remain in the air longer than large droplets.

2. How to clean, reuse or hack a coronavirus mask
Tips to extend the life, sanitize, and make your mask more effective
1. Treat your mask like a biohazard.
2. Wash your hands with soap every time you remove or even touch the mask.

3. How to clean homemade cloth face masks and the best material to make one
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 According to a study published in Disaster Medicine and Public Health Preparedness, homemade masks made from a kitchen towel proved to be the most effective at removing particles.
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The choice of fabric is very important. Professor Koehler suggests using tightly woven fabric folded in multiple layers. A research paper published in PeerJ confirms the fabric concern. The study looked at the surface of 20 different types of cloth masks and found the size of pores in masks ranged from 80 to 500 micrometers. For comparison, the novel coronavirus is about 0.12 micrometers:
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You should not clean an N95 mask at home. But you can reuse it with proper care. Here's how:
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Chandrasekhi

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Re: Of Masks and Man
« Reply #14 on: January 28, 2021, 10:12:59 am »
Quote
https://www.businessinsider.co.za/your-n95-mask-is-likely-fake-heres-how-to-tell-if-its-keeping-you-safe-2020-12
Fake N95 and KN95 masks on frontlines and in SA stores. Here’s how to tell if yours is real
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N95 masks are the gold standard for preventing the transmission of Covid-19 in a heath care environment.
But global markets have been flooded with fake equivalents and a range of Chinese-made KN95 mask.
A recent study by UCT found that 12 manufacturers were selling ineffective KN95 masks onto SA's frontlines.
And some South Africa stores are also carrying dodgy-looking masks with claims that they are N95 and KN95 certified.
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