Face Mask Technologies

This forum is to discuss general things concerning TSOI.
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Re: Face Mask Technologies

Post by trader32176 »

N95 vs. KN95 vs. KF94 masks: What's the difference and which should you use?

Learn which type of mask best prevents the spread of COVID-19.


https://www.cnet.com/health/n95-vs-kn95 ... d-you-use/

It's a year later and we're all wearing face masks, something most of us never imagined last February. Health experts even recommend wearing two masks at once now. As more COVID-19 variants appear, wearing a high-quality face mask is more important than ever.

We already know that all face masks aren't equal, and there's a difference between medical-grade respirators and cloth face coverings. Now as the pandemic drags on, professional-grade masks are gaining attention again, especially because they can filter out particles better than a cloth mask. This guide compares N95 masks, KN95 masks and KF94 masks -- three popular and protective types of mask -- to help you make smart mask-buying and mask-wearing decisions.

N95 masks

Percentage of aerosol particulates filtered: 95%
NIOSH-approved: Yes
Who should wear one: Health care workers only

N95 masks have been popular since the early stages of the pandemic in 2020. These masks give an extremely tight fit thanks to elastic headbands and an adjustable metal seal over the nose, which keeps the mask close to your skin.

They filter 95% of particles as small as 0.3 microns in size. (Although SARS-CoV-2 virus particles are about 0.1 microns in size by themselves, remember that virus particles are usually attached to something bigger, like the respiratory droplets generated when talking).

N95s undergo the rigorous inspection and certification set forth by the National Institute for Occupational Safety and Health, and only after being certified are they approved as medical-grade masks. A study in the Journal of the American Medical Association calls N95s the "mainstay of protection against airborne pathogens."

Unfortunately, these masks have been in short supply for nearly a year now because they are part of the personal protective equipment health care workers need when treating patients with COVID-19. As such, the Centers for Disease Control and Prevention recommends that N95s be reserved for health care workers only, not for the general public.

KN95 masks

Percentage of aerosol particulates filtered: 95%
NIOSH-approved: No
Who should wear one: Anyone can wear these masks in low- to moderate-risk environments, such as going to the grocery store or an outdoor gathering.

KN95 masks are considered the Chinese equivalent of N95 masks. They feature a tentlike shape that creates a little pocket of air between your nose and the fabric, which makes them appealing to many people: They feel easier to breathe through, less obstructive and stifling.

However, because KN95 masks aren't overseen by the mask-regulating body in the US, NIOSH, they aren't considered as effective as N95 masks. Manufacturers of KN95s can seek emergency use authorization from the FDA for use in health care settings. In fact, the FDA has granted EUA to several KN95 masks already.

In September 2020, a report from the Emergency Care Research Institute raised concerns over fraudulent KN95 masks. According to the report, up to 70% of KN95 masks imported from China don't meet the same filtration efficacy as N95 masks. ECRI issued an alert because many hospitals were ordering these masks, which could pose contamination risks in medical centers where patients are being treated for COVID-19.

Outside of health care and high-risk settings, this isn't necessarily a big deal. The general public can benefit from wearing KN95 masks. Even KN95 masks that don't meet NIOSH standards for filtration efficacy are probably still more protective than basic surgical masks and cloth face masks made of cotton, nylon or another non medical fabric.

KF94 masks

Percentage of aerosol particulates filtered: 94%
NIOSH-approved: No
Who should wear one: Anyone can wear these masks in low- to moderate-risk environments, such as going to the grocery store or an outdoor gathering.

KF94 masks are now growing in popularity. The "KF" stands for "Korean filter" and the 94 refers to the masks' filtration efficacy. According to the South Korean government's standards, these masks filter 94% of particles down to 0.3 microns in size. They feature ear loops, an adjustable nose bridge and side flaps to create a tight fit.

In a very small August 2020 study (only seven people), researchers found KF94 masks to be just as effective at filtering SARS-CoV-2 as N95 masks. However, unlike KN95s that meet the Chinese government's standards of certification, KF94 masks have not yet been granted EUA from the FDA for use in health care settings.

Still, like KN95s, KF94s are a steep upgrade from the single-ply cotton face cover you're probably walking around with.

Avoiding counterfeit masks

Fraudulent face masks have become a problem on Amazon and other large online retailers. Manufacturers claim to be selling N95s, KN95s or KF94s, when in reality the masks they sell are not held to the same standards as masks that have undergone inspection by the US, Chinese or Korean governments. The CDC has a running list of non-NIOSH-approved KN95s, KF94s and other protective masks that have gone through filtration testing. The list also includes known counterfeits.

It's near-impossible to spot counterfeit masks, especially when shopping online, but you can take a few steps to ensure that you're getting the best protection possible:

Buy from reputable retailers, such as CVS or Walgreens, which have vetting processes for wholesale products.
Look closely at seller ratings and product reviews
Be wary of new sellers that seem to pop up out of nowhere
Check the product listing and URL to make sure the names match
Double-mask if you're unsure of the quality of your masks
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Re: Face Mask Technologies

Post by trader32176 »

Health Workers and Hospitals Grapple With Millions of Counterfeit N95 Masks


https://khn.org/news/article/health-wor ... n95-masks/

Thousands of counterfeit 3M respirators have slipped past U.S. investigators in recent months, making it to the cheeks and chins of health care workers and perplexing experts who say their quality is not vastly inferior to the real thing.

N95 masks are prized for their ability to filter out 95% of the minuscule particles that cause covid-19. Yet the fakes pouring into the country have fooled health care leaders from coast to coast. As many as 1.9 million counterfeit 3M masks made their way to about 40 hospitals in Washington state, according to the state hospital association, spurring officials to alert staff members and pull them off the shelf. The elite Cleveland Clinic recently conceded that, since November, it had inadvertently distributed 3M counterfeits to hospital staffers. A Minnesota hospital made a similar admission.

Nurses at Jersey Shore University Medical Center have been highly suspicious since November that the misshapen and odd-smelling “3M” masks they were given are knockoffs, their concerns fueled by mask lot numbers matching those the company listed online as possible fakes.

“People have been terrified for the last 2½ months,” said Daniel Hayes, a nurse and union vice president at the New Jersey hospital. “They felt like they were taking their lives in their hands, and they don’t have anything else to wear.”

According to 3M, the leading U.S. producer of N95s, more than 10 million counterfeits have been seized since the pandemic began and the company has fielded 10,500 queries about the authenticity of N95s. The company said in a Jan. 20 letter that its work in recent months led to the seizure of fake 3M masks “sold or offered to government agencies” in at least six states. After KHN sent photos of the masks the New Jersey nurses questioned, a 3M spokesperson referred to them as “the counterfeits you identified.”

At KHN’s request, ECRI agreed to test the masks that sparked the New Jersey nurses’ concern. Tests of a dozen masks showed they filtered out 95% or more of the 0.3-micron particles they’re expected to catch. (ECRI is a nonprofit that helps health providers assess the quality of medical technology.)

ECRI engineering director Chris Lavanchy said several health organizations across the U.S. have recently made similar requests for tests of apparently fake 3M masks that the company warned about.

Lavanchy said the results have shown similarly high filtration levels, but also higher breathing resistance than expected. He said such resistance can fatigue the person wearing the mask or cause it to lift off the face, letting in unfiltered air.

“We’re kind of scratching our heads trying to understand this situation, because it’s not as black-and-white as I would have expected,” Lavanchy said. “I’ve looked at other masks we knew were counterfeit and they usually perform terribly.”

3M spokesperson Jennifer Ehrlich said a critical feature of N95 masks, aside from filtration, is how well they fit.

“Without a proper seal and fit, respirators are not filtering [properly] — gaps could allow air to enter,” Ehrlich said via email.

The materials management team for Hackensack Meridian Health, which owns the Jersey Shore hospital, is “working with an independent lab on validating the quality and compliance of specific lot numbers of 3M N95 respirators the company identified as potentially problematic,” according to a company statement.

When the Washington State Hospital Association purchased 300,000 N95s in December, it sent samples to hospital leaders, who said they appeared legitimate.

“It’s not like we just ordered them sight unseen,” said Beth Zborowski, spokesperson for the association. “We had two major medical centers in Seattle … look at the quality, straps, cut them open and decide ‘This looks like it’s the real deal’ before they bought them.”

She said major hospital systems in the state bought more on their own, adding up to 1.9 million.

Throughout the pandemic, workers have also been provided with Chinese-made KN95 masks — approved by U.S. regulators on an emergency basis — that turned out to be far less effective than billed.

In April, the Food and Drug Administration, responding to dire shortages of high-quality masks for health care workers, opened the door to KN95s, which are supposed to offer the same level of protection as N95s.

Yet, as months passed, researchers from the Centers for Disease Control and Prevention, Harvard, MIT and ECRI discovered that KN95s did not meet the high standard: 40% to 70% of the KN95s failed their tests and some filtered out only 30% of the tiny particles.

More than 3,400 front-line health care workers have died during the pandemic, KHN and The Guardian have found in the ongoing Lost on the Frontline project, and many families have raised concerns about inadequate protective gear. Yet the actual harm that any substandard or knockoff device presents remains difficult to assess.

Researchers say it’s unethical to conduct a study that involves giving health workers a product they know is less protective than another when lives are at stake. And short of performing in-depth genome sequencing on each worker’s viral strain, it’s hard to know exactly how any person got sick.

At the U.S. border, safeguarding the medical gear supply is a high priority, said Michael Rose, a section chief in U.S. Immigration and Customs Enforcement’s global trade division.

His job for the past year has been investigating a wide variety of covid-related scams. Of all those cases, Rose said, the flood of fake 3M masks from China has been the most consistent.

“It’s definitely cat and mouse,” Rose said. “Where we might get better [at intercepting counterfeits], they can ship elsewhere, change the name of the company and keep going.”

Many investigations lead to seizures in the nation’s massive ports of entry, where enormous cargo ships and planes carry giant containers of goods. There, agents might spot a dead giveaway like a box just off a ship from Shenzhen, China, marked “3M” and “Made in the USA.”

“I’d like to say that makes it easier, and it does, but the sheer volume of them coming in …” he said. “It’s like a needle in a stack of needles.”

The demand for highly protective masks has surged twelvefold during the pandemic, said Chaun Powell, vice president of disaster response for Premier, a major hospital supply company. The national medical use of N95s used to be about 25 million a year, but it soared to 300 million last year, he said.

That meant hospitals and other health providers couldn’t rely on their usual sources of products to meet their need for personal protective gear.

Health care providers “had to find alternatives,” Powell said, “and that created opportunities for fraudulent manufacturers to be opportunistic and sneak in.”

Many of Rose’s investigations originate from customer complaints about apparent fakes to 3M, which forwards reports to his team. Others come from hospitals, health systems or eagle-eyed first responders who email Covid19fraud@dhs.gov.

Border Patrol agents, working with Rose’s team and anticipating shipments from known counterfeiters, have seized thousands of fake N95s in recent weeks, including 100,080 at a port of entry near El Paso, Texas, in December and 144,000 flown from Hong Kong to New York. In all, federal officials say, they have seized more than 14.5 million masks, many fake 3Ms but other counterfeit cloth or surgical masks as well.

In New Jersey, staff members began complaining in November about their masks to union leaders at Jersey Shore University Medical Center, said Kendra McCann, president of the hospital’s Health Professionals and Allied Employees union local.

The masks, which seemed flimsy and made some workers’ faces burn, were turning up in every unit of the hospital. After a union member discovered a letter on the 3M website pinpointing their mask lots as potentially fake, managers began to remove the masks but suspected fakes continued to turn up, McCann said.

Hackensack Meridian said a daily call with hospital leaders includes “reminders to report any suspect PPE so that it can be removed immediately and evaluated.”

The episode added stress to caregivers who are terrified about getting infected and bringing the virus into their own homes.

“Nurses are scared to death,” McCann said in mid-January as the masks continued to pop up, “because they’re not being provided with the proper PPE.”
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Re: Face Mask Technologies

Post by trader32176 »

Fit of face masks is more important than material to provide best protection against COVID-19


https://www.news-medical.net/news/20210 ... ID-19.aspx

A team of researchers studying the effectiveness of different types of face masks has found that in order to provide the best protection against COVID-19, the fit of a mask is as important, or more important, than the material it is made of.

The researchers, from the University of Cambridge, carried out a series of different fit tests, and found that when a high-performance mask - such as an N95, KN95 or FFP2 mask - is not properly fitted, it performs no better than a cloth mask. Minor differences in facial features, such as the amount of fat under the skin, make significant differences in how well a mask fits.

The results, published in the journal PLoS ONE, also suggest that the fit-check routine used in many healthcare settings has high failure rates, as minor leaks may be difficult or impossible to detect by the wearer. While the sample size was small, the researchers hope their findings will help develop new fit tests that are quick and reliable, in the case of future public health emergencies.

The current study only evaluated the impact of fit on the wearer of the mask - the team will evaluate how fit impacts the protection of others in future research.

The COVID-19 pandemic has made well-fitting face masks a vital piece of protective equipment for healthcare workers and civilians. While the importance of wearing face masks in slowing the spread of the virus has been demonstrated, there remains a lack of understanding about the role that good fit plays in ensuring their effectiveness.

" We know that unless there is a good seal between the mask and the wearer's face, many aerosols and droplets will leak through the top and sides of the mask, as many people who wear glasses will be well aware of. We wanted to quantitatively evaluate the level of fit offered by various types of masks, and most importantly, assess the accuracy of implementing fit checks by comparing fit check results to quantitative fit testing results."

- Eugenia O'Kelly, Paper's First Author, Cambridge's Department of Engineering

For the study, seven participants first evaluated N95 and KN95 masks by performing a fit check, according to NHS guidelines. Participants then underwent quantitative fit testing - which uses a particle counter to measure the concentration of particles inside and outside the mask - while wearing N95 and KN95 masks, surgical masks, and fabric masks. The results assessed the protection to the mask wearer, which is important in clinical settings.

N95 masks - which are a similar standard to the FFP3 masks available in the UK and the rest of Europe - offered higher degrees of protection than the other categories of masks tested; however, most N95 masks failed to fit the participants adequately.

In their study, the researchers found that when fitted properly, N95 masks filtered more than 95% of airborne particles, offering superior protection. However, in some cases, poorly-fitted N95 masks were only comparable with surgical or cloth masks.

"It's not enough to assume that any single N95 model will fit the majority of a population," said O'Kelly. "The most widely-fitting mask we looked at, the 8511 N95, fit only three out of the seven participants in our study."

One observation the researchers made during their study was the width of the flange of the mask - the area of the material which comes in contact with the skin - may be a critical feature to fit. Masks which fit the greatest number of participants tended to have wider, more flexible flanges around the border.

In addition, small facial differences were observed to have a significant impact on quantitative fit. "Fitting the face perfectly is a difficult technical challenge and, as our research showed, small differences such as a centimetre wider nose or slightly fuller cheeks can make or break the fit of a mask," said O'Kelly.

Self-performed fit-checks are attractive because they save on time and resources, and are often the only method of fit testing available. However, this study, and studies of fit-check systems in other countries, indicate that such fit-check systems are not reliable.

The researchers hope that their results will be of use for those who are working on new technologies and programmes to assess fit, so that healthcare and other frontline workers are adequately protected in the case of any future pandemics. Additionally, they hope these results will bring attention to the importance of fit in clinical-grade masks, especially if such masks are to be widely used by the public. This study did not evaluate the impact of fit on protecting others, which is a future area of research.


University of Cambridge

Journal reference:

O’Kelly, E., et al. (2021) Comparing the fit of N95, KN95, surgical, and cloth face masks and assessing the accuracy of fit checking. PLOS ONE. doi.org/10.1371/journal.pone.0245688.
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Re: Face Mask Technologies

Post by trader32176 »

Self-assessment of face coverings lowers protection against SARS-CoV-2


https://www.news-medical.net/news/20210 ... CoV-2.aspx

Researchers in the United States have conducted a study demonstrating that personal assessment of whether respirators and face masks fit properly cannot be relied on in efforts to protect against infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

The SARS-CoV-2 virus is the agent responsible for the coronavirus disease 2019 (COVID-19) pandemic that has threatened to overwhelm healthcare services in many countries across the globe.

The pandemic has meant well-fitting respirators and face masks have become crucial pieces of protective equipment among healthcare workers and the general public.

However, supply chain constraints have caused some organizations to replace traditional qualitative and quantitative “fit” testing with self-performed fit checks.

As reported in the journal PLOS ONE, researchers from Cambridge University in San Francisco and Northwestern University in Evanston have shown that a fit check performed according to UK National Health Service (NHS) self-assessment guidelines was unreliable in determining the fit of face coverings.

Most N95 respirators failed to fit participants adequately and fit check responses across all face coverings tested correlated poorly with quantitative fit factor scores.

The importance of well-fitting face masks

The COVID-19 pandemic has highlighted not only the importance of wearing face coverings but also the necessity to ensure a good fit that will reduce the spread of viral particles.

“The importance of fit for N95 respirators has particular implications during the COVID-19 pandemic as these masks are generally reserved for clinicians at a time when hospitals are struggling to cope with the demand for conventional fit testing,” says O’Kelly and colleagues. “Even a small fit issue not detected by the wearer when performing a fit check can greatly decrease the protection offered by the N95 respirator.”

However, constraints on the supply of face masks and fit testing during the pandemic has led many healthcare facilities to replace traditional quantitative and qualitative testing procedures with self-performed tests. Such tests involve the user checking for air leaks and assessing how the mask responds to heavy breathing.

The potential impact of replacing fit testing procedures with self-performed checks is not well understood.

In terms of settings outside of healthcare facilities, there is also a lack of literature exploring the effects of fit on the protection provided by face coverings.

What did the researchers do?

Seven individuals (median age 51 years) self-performed fit checks of N95 and KN95 respirators according to UK NHS guidelines.

Participants then underwent quantitative fit testing while wearing different types of N95 respirators, a KN95 respirator, different surgical masks, and a range of fabric face coverings. Quantitative fit testing involves the continuous measurement of particle concentration both inside and outside of the face-covering while it is being worn.

The researchers evaluated the level of fit and protection provided by each type of mask and how well self-performed checks predicted fit, compared with quantitative testing.

What did they find?

“Fit is critical to the level of protection offered by respirators,” says O’Kelly ad colleagues.

When N95 respirators were properly fitted, they filtered more than 95% of airborne particles, while poorly fitting respirators provided variable levels of protection that were sometimes similar to the levels provided by surgical and cloth masks.

The N95 respirators provided higher levels of protection than any other category of mask, but 4 out of 7 participants were unable to fit the respirators properly.

Participants were generally unable to reliably determine whether respirators fitted properly, with all of them making at least one incorrect determination of fit after performing a check.

“Our results indicate that the method of fit check for N95 respirators, which is being used in many hospitals, is not reliable and has similar failure rates as previously tested self-assessment protocols,” writes the team.

What about the other types of face-covering?

The study also found that KN95 respirators, surgical masks and fabric masks all achieved similarly low fit factor scores and did not significantly differ in the level of protection they provided.

“For civilian protection, no one type of mask proved superior to another. This is likely due to poor fit in the civilian mask options,” say the researchers.

“Participants were seen to achieve similar protection from a fabric face covering as from a KN95 respirator, whose material should perform similarly to an N95 respirator,” they add.

What do the authors advise?

O’Kelly and colleagues say the findings suggest that traditional quantitative or qualitative fit testing for individuals is highly advisable for people in need of respiratory protection.

“The high proportion of fit test failures, and the associated reduction in the effectiveness, has particular implications for healthcare facilities and other work-environments where fit testing may be abandoned during a pandemic,” they write.

“Having a wide variety of mask models and sizes stockpiled is critical as one mask model cannot be assumed to protect the majority of wearers,” advises the team.

Journal reference:

O’Kelly E, et al. Comparing the fit of N95, KN95, surgical, and cloth face masks and assessing the accuracy of fit checking. PLOS ONE, 2021. https://doi.org/10.1371/journal.pone.0245688

The results showed that a proper fit is essential to ensuring N95 respirators provide high levels of protection.
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Re: Face Mask Technologies

Post by trader32176 »

Researchers develop nanoceutical mask fabric that prevents SARS-CoV-2 transmission


https://www.news-medical.net/news/20210 ... ssion.aspx

As the coronavirus disease 2019 (COVID-19) continues to spread globally, countries are adapting to the new normal. This includes wearing face masks, protective clothing, face shields, and practicing social distancing.

These non-pharmacological interventions (NPIs) can help mitigate the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19.

Face masks have become normal paraphernalia for people, even those who are not health workers. Initially, masks were intended to protect surrounding people. Now, wearers also use face masks to protect themselves from others.

Finding an effective, antimicrobial, and comfortable fabric for face masks and personal protective clothing (PPE) is necessary to ensure that wearers are protected from virus-laden respiratory droplets from infected individuals.

Researchers at S N Bose National Centre for Basic Sciences in West Bengal found that a nanoceutical fabric, which is comfortable, washable, and anti-microbial, can prevent the transmission of the virus.

Face mask issues

Personal protective equipment (PPE) covers a wide range of materials and tools used to reduce the transmission of respiratory droplets from infected individuals. Apart from protecting others, it can also protect the wearer from contracting the virus.

The U.S. Centers for Disease Control and Prevention (CDC) warned against the use of one-way vents or valves in face masks since these can facilitate the viral transmission. It can also cause severe discomfort and health problems.

Past studies have suggested that commonly available N95 face masks can cause changes in blood oxygen and carbon dioxide levels when used for long periods. These changes are commonly seen in people who are older, obese, or have chronic obstructive pulmonary disease (COPD).

Other health effects include increased heart rate, elevated blood pressure, hypercapnia or increased carbon dioxide levels, and chest pain. One of the solutions is to cover the vent with a porous filter that can trap or kill microbes like viruses.

To date, there is still no study to develop such filters. Developing filters made of natural fabrics embedded with antimicrobial agents could be an effective solution.

The study

The study, published on the preprint journal bioRxiv* server, explored the use of a novel nanoceutical cotton fabric duly sensitized with non-toxic zinc oxide (ZnO) nanoflower that can be used as membrane filter in the one-way valve of face mask to ensure breathing comfort. Apart from this, it can also protect the wearer from COVID-19 infection.

The nanoceutical fabric can alter the SARS-CoV-2 spike protein, making the virus ineffective.

To arrive at the study findings, the researcher team conducted a comprehensive computer-assisted simulation study, revealing the unique potential of ZnO nanoflowers. These have two-dimensional nanopetals in trapping and denaturation of the SARS-CoV-2 spike protein, killing the virus.

Further, the team synthesized the ZnO NF on natural cotton fiber matrix by a one-pot hydrothermal assisted approach. They also tested the fabric’s antimicrobial properties through an exhaustive antimicrobial study using a capsule containing Pseudomonas aerugnosa, which shares similar homology to coronavirus spike protein.

The study findings showed that the developed nanoceutical fabric filter has outstanding antimicrobial efficiency.

To our understanding, the novel nanoceutical fabric used in one-way valve of a face mask would be the choice to assure breathing comfort along with source control of COVID-19 infection,” the team noted in the paper. “The developed nanosensitized cloth can further be used as antibacterial (as well as anti-SARS CoV-2) dress material, in general, to stop the hospital-acquired infection,” they added.

The research team has successfully used commonly available cotton fabrics infused with ZnO nanoflowers. The resulting product was effective in destroying the microbial membrane, inhibiting the infection.

To further test the product, they designed a laboratory-grade prototype respiratory using a regular N95 mask with the ZnO nanoflower cotton fabrics. The respiratory, which was porous and light-weight, solved the common problem of carbon dioxide rebreathing and prevented the spread of microbes through the pores.

The new product could be used in the production of masks and PPEs, which are urgently needed today, particularly by health workers in the front lines of the pandemic fight.

To date, there are more than 111.75 million cases of COVID-19 worldwide. Of these, 2.47 million people have died.

*Important Notice

bioRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.


COVID-19 Dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University (JHU) - https://gisanddata.maps.arcgis.com/apps ... 7b48e9ecf6

Journal reference:

Adhikari, A., Pal,. U., Bayan, S. et al. (2021). Nanoceutical Fabric Prevents COVID-19 Spread through Expelled Respiratory Droplets: A Combined Computational, Spectroscopic and Anti-microbial Study. bioRxiv. doi: https://doi.org/10.1101/2021.02.20.432081, https://www.biorxiv.org/content/10.1101 ... 0.432081v1
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Re: Face Mask Technologies

Post by trader32176 »

Study shows why three-layered masks are safer than single or double-layered alternatives


https://www.news-medical.net/news/20210 ... tives.aspx

If you are going to buy a face mask to protect yourself and others from COVID-19, make sure it's a three-layered mask. You might have already heard this recommendation, but researchers have now found an additional reason why three-layered masks are safer than single or double-layered alternatives.

While this advice was originally based on studies that showed three layers prevented small particles from passing through the mask pores, researchers have now shown that three-layered surgical masks are also most effective at stopping large droplets from a cough or sneeze from getting atomized into smaller droplets.

These large cough droplets can penetrate through the single- and double-layer masks and atomize to much smaller droplets, which is particularly crucial since these smaller droplets (often called aerosols) are able to linger in the air for longer periods of time.

Researchers studied surgical masks with one, two, and three layers to demonstrate this behavior.

The researchers reported their results in Science Advances on March 5.

The team notes that single and double-layer masks do provide protection in blocking some of the liquid volumes of the original droplet and are significantly better than wearing no mask at all.

They hope their findings on ideal mask pore size, material thickness, and layering could be used by manufacturers to produce the most effective mask designs.

Using a droplet generator and a high-speed time-lapse camera, the team of engineers from the University of California San Diego, Indian Institute of Science, and the University of Toronto found that, counterintuitively, large respiratory droplets containing virus emulating particles (VEPs) actually get atomized when they hit a single-layer mask, and many of these VEPs pass through that layer.

Think of it like a water droplet breaking into smaller droplets as it's being squeezed through a sieve.

For a 620 micron droplet-; the size of a large droplet from a cough or sneeze-; a single-layer surgical mask only restricts about 30 percent of the droplet volume; a double-layer mask performs better, restricting about 91 percent of the droplet volume; while a three-layer mask has negligible, nearly zero droplet ejection. This video illustrates the research as well.

"While it is expected that large solid particles in the 500–600-micron range should be stopped by a single-layer mask with an average pore size of 30 microns, we are showing that this is not the case for liquid droplets," said Abhishek Saha, professor of mechanical and aerospace engineering at UC San Diego and a co-author of the paper.

"If these larger respiratory droplets have enough velocity, which happens for coughs or sneezes when they land on a single-layer of this material it gets dispersed and squeezed through the smaller pores in the mask."

This is a problem. Droplet physics models have shown that while these large droplets are expected to fall to the ground very quickly due to gravity, these now smaller, 50-80 micron-sized droplets coming through the first and second layer of a mask will linger in the air, where they can spread to people at larger distances.

The team of engineers-; which also includes Professors Swetaprovo Chaudhuri from the University of Toronto, and Saptarshi Basu of the Indian Institute of Science-; were well-versed in this type of experiment and analysis, though they were used to studying the aerodynamics and physics of droplets for applications including propulsion systems, combustion, or thermal sprays.

They turned their attention to respiratory droplet physics last year when the COVID-19 pandemic broke out, and since then, have been studying the transport of these respiratory droplets and their roles in the transmission of Covid-19 type diseases.

" We do droplet impact experiments a lot in our labs. For this study, a special generator was used to produce a relatively fast-moving droplet. The droplet was then allowed to land on a piece of mask material-; that could be a single layer, double, or triple-layer, depending on which we're testing. Simultaneously, we use a high-speed camera to see what happens to the droplet."

- Abhishek Saha, Study Co-Author and Professor of Mechanical Aerospace Engineering, University of California San Diego

Using the droplet generator, they're able to alter the size and speed of the droplet to see how that affects the flow of the particle.

Going forward, the team plans to investigate the role of different mask materials, as well as the effect of damp or wet masks, on particle attrition.


University of California San Diego

Journal reference:

Sharma, S., et al. (2021) On secondary atomization and blockage of surrogate cough droplets in single- and multilayer face masks. Science Advances. doi.org/10.1126/sciadv.abf0452.
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Re: Face Mask Technologies

Post by trader32176 »

How is speech recognition affected by face masks?


https://www.news-medical.net/news/20210 ... masks.aspx

What provoked your research efforts into the ongoing COVID-19 pandemic?

Our research focuses on questions about speech perception and language processing more broadly.

We were interested in studying the effects of face masks, in particular, given the widespread use of masks to help prevent the spread of COVID-19 and possible concerns over how they might affect speech recognition.

Can you give an overview of the different types of face masks available?

In our study, we looked at four types of masks: a surgical mask, an N95 respirator, and two homemade cloth masks (one with a fitted design and one with a pleated design). Cloth masks have been used by the general public during the pandemic, whereas N95 masks are used by healthcare professionals.

We were particularly interested in the effects of the homemade masks since many people use these types of masks every day and there was only limited previous research on how they might impact speech recognition.

How does background noise affect hearing?

Background noise can have a large impact on hearing, though listeners with normal hearing are generally very good at recognizing speech even in background noise. The type of noise we looked at in our study is called multi-talker babble, which consists of multiple talkers speaking at the same time (six talkers in our study). It sounds similar to what you might hear in a crowded restaurant.

Also, it is important to note that, for listeners with hearing difficulty, background noise can have an even bigger effect. In our study, we only looked at effects for listeners with normal hearing.

Can you describe how you carried out your latest research into face masks and speech recognition?

We presented listeners with spoken sentences and asked them to type the sentence that they heard. Sentences were presented in the multi-talker babble noise, in either a relatively easy condition with low levels of noise or a difficult condition with high levels of noise. We recorded sentences while wearing each of the four masks and when wearing no mask.

In all the conditions, the listeners only heard the sentences—there was no visual information like you would get in face-to-face communication. As a result, the study just focused on the auditory effects of the masks. The loss of visual information could play an additional role in face-to-face settings.

What did you discover?

We found that, in low levels of background noise, typical of noise levels in many everyday settings, listeners were very good at recognizing speech produced without a mask, as we expected. They correctly recognized 94.3% of the words in the sentences for this condition.

For speech produced with the masks, they also did rather well, particularly for speech produced with the surgical mask, where they were 93.5% accurate. Overall, masks had relatively small effects in this condition.

In contrast, when the background noise was very high, listeners were only 45.2% correct for speech produced without a mask, demonstrating that this was a very difficult listening condition. Here, we found larger differences between the masks. The surgical mask again led to the best performance among the masks, and listeners were less accurate for the N95 and cloth masks.

Prior research has been conducted into speech recognition whilst wearing masks but has had limited sample sizes and other limitations. How did your research overcome some of these limitations?

We used a large sample size (181 participants) in this study. We also tested conditions that were both relatively easy (low levels of background noise) and more challenging (high levels of background noise).

Previous studies had looked at some of these conditions for certain types of masks on their own, and overall, the effects we found in the current study matched what we would expect based on that previous research.

What are the next steps in your research?

We would like to investigate a wider variety of masks and look at the effects of double-masking. We would also like to know how people have adapted to listening to speech while wearing a mask over the past year.

Listeners are very good at adapting to novel listening conditions, and they may have gotten better over time at understanding speech produced while wearing a mask.

Where can readers find more information?


This material is based upon work supported by the National Science Foundation under Grant No. 1945069. Any opinions, findings, and conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
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Re: Face Mask Technologies

Post by trader32176 »

New copper-based foam filter could be used in facemasks or air filtration systems


https://www.news-medical.net/news/20210 ... stems.aspx

During the COVID-19 pandemic, people have grown accustomed to wearing facemasks, but many coverings are fragile and not easily disinfected. Metal foams are durable, and their small pores and large surface areas suggest they could effectively filter out microbes. Now, researchers reporting in ACS' Nano Letters have transformed copper nanowires into metal foams that could be used in facemasks and air filtration systems. The foams filter efficiently, decontaminate easily for reuse and are recyclable.

When a person with a respiratory infection, such as SARS-CoV-2, coughs or sneezes, they release small droplets and aerosolized particles into the air. Particles smaller than 0.3 µm can stay airborne for hours, so materials that can trap these tiny particles are ideal for use in facemasks and air filters. But some existing filter materials have drawbacks. For example, fiberglass, carbon nanotubes and polypropylene fibers are not durable enough to undergo repeated decontamination procedures, while some further rely on electrostatics so they can't be washed, leading to large amounts of waste.

Recently, researchers have developed metallic foams with microscopic pores that are stronger and more resistant to deformation, solvents, and high temperatures and pressures. So, Kai Liu and colleagues wanted to develop and test copper foams to see if they could effectively remove submicron-sized aerosols while also being durable enough to be decontaminated and reused.

The researchers fabricated metal foams by harvesting electrodeposited copper nanowires and casting them into a free-standing 3D network, which was solidified with heat to form strong bonds. A second copper layer was added to further strengthen the material. In tests, the copper foam held its form when pressurized and at high air speeds, suggesting it's durable for reusable facemasks or air filters and could be cleaned with washing or compressed air.

The team found the metal foams had excellent filtration efficiency for particles within the 0.1-1.6 µm size range, which is relevant for filtering out SARS-CoV-2. Their most effective material was a 2.5 mm-thick version, with copper taking up 15% of the volume. This foam had a large surface area and trapped 97% of 0.1-0.4 µm aerosolized salt particles, which are commonly used in facemask tests. According to the team's calculations, the breathability of their foams was generally comparable to that of commercially available polypropylene N95 facemasks. Because the new material is copper-based, the filters should be resistant to cleaning agents, allowing for many disinfection options, and its antimicrobial properties will help kill trapped bacteria and viruses, say the researchers. In addition, they are recyclable.

The researchers estimate that the materials would cost around $2 per mask at present, and disinfection and reuse would extend their lifetime, making them economically competitive with current products.


American Chemical Society (ACS)

Journal reference:

Malloy, J., et al. (2021) Efficient and Robust Metallic Nanowire Foams for Deep Submicrometer Particulate Filtration. Nano Letters. doi.org/10.1021/acs.nanolett.1c00050.
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Re: Face Mask Technologies

Post by trader32176 »

BOMBSHELL: Disposable blue face masks found to contain toxic, asbestos-like substance that destroys lungs


https://outbreak.news/2021-03-30-blue-m ... lungs.html

Health Canada has issued a warning about blue and gray disposable face masks, which contain an asbestos-like substance associated with “early pulmonary toxicity.”

The SNN200642 masks, which are made in China and sold and distributed by a Quebec-based company called Métallifer, had been part of Canada’s public school reopening plan. Students were told that they needed to wear them in the classroom to prevent the spread of the Wuhan coronavirus (Covid-19).

Health Canada, however, discovered during a preliminary risk assessment that the masks contain microscopic graphene particles that, when inhaled, could cause severe lung damage.

“Graphene is a strong, very thin material that is used in fabrication, but it can be harmful to lungs when inhaled and can cause long-term health problems,” reported CBC News.

For a while now, some daycare educators had expressed suspicion about the masks, which were causing children to feel as though they were swallowing cat hair while wearing them. We now know that instead of cat hair, children were inhaling the equivalent of asbestos all day long.

“If you have this type of mask in stock, we ask that you stop distributing them and keep them in a safe place now,” the provincial government wrote in a directive, which was sent to the education, families, and higher education ministries of Canada.
Face masks are neither safe nor effective

As it turns out, the SNN200642 masks that were being used all across Canada in school classrooms had never been tested for safety or effectiveness. Patrick Baillargeon, who heads up purchasing for Quebec’s laboratory supplies, says that because of this, the masks never should have been used.

The risks associated with inhaling graphene particles is unacceptable, he added, and Canadians – and everyone else, for that matter – should immediately stop using the masks.

“We therefore ask all our customers to check if they have any in their possession,” Baillargeon wrote in a notice, further revealing that at the time of their acquisition and distribution, the blue and gray disposable face masks were not in compliance with government regulations.

Schools and other facilities adopted them due to fears surrounding the Chinese virus, but this rushed, reactionary response is now causing other problems in the form of lung damage.

“We are now verifying whether any of these particular masks remain in our schools and centres,” reads a letter sent by the Lester B. Pearson school board to the parents of all exposed children.

“Any unused masks will be returned to our storage depot while we await further directives from the government.”

Back in December, the Quebec government had distributed these toxic masks to more than 15,000 daycare centers throughout the province. None of the masks met safety standards and were later ordered to no longer be used.

Another similar style of disposable mask, known as MC9501, was likewise pulled from distribution throughout Canada after it was determined to be unsafe. As many as 31.1 million toxic masks from this line were distributed before the government realized that they are unfit for use.

“Shouldn’t all this stuff be tested BEFORE it even leaves the factory?” asked one CBC News commenter, expressing outrage over the government’s act now, think later approach to Wuhan flu mitigation.

Others called for heads to roll over the fiasco, as well as an immediate end to all face mask use as the coverings are both useless and harmful no matter what materials were used in their production.

“To force a child to wear a toxic face mask is child abuse,” one wrote. “I hope lawsuits will follow.”
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Re: Face Mask Technologies

Post by trader32176 »

Type of material used in face masks and fabric layers can affect Covid-19 exposure risk


https://www.news-medical.net/news/20210 ... -risk.aspx

Wearing a face mask can protect yourself and others from Covid-19, but the type of material and how many fabric layers used can significantly affect exposure risk, finds a study from the Georgia Institute of Technology.

The study measured the filtration efficiency of submicron particles passing through a variety of different materials. For comparison, a human hair is about 50 microns in diameter while 1 millimeter is 1,000 microns in size.

" A submicron particle can stay in the air for hours and days, depending on the ventilation, so if you have a room that is not ventilated or poorly ventilated then these small particles can stay there for a very long period of time."

- Nga Lee (Sally) Ng, Associate Professor and Tanner Faculty Fellow in the School of Chemical and Biomolecular Engineering and the School of Earth and Atmospheric Sciences

The study was conducted during spring 2020, when the pandemic triggered a global shutdown of most institutions. Communities faced massive shortages of personal protective equipment, prompting many people to make their own homemade masks. Georgia Tech quickly set up the study since it already had "a great system for testing filtration efficiency using existing instruments in the lab," Ng recalled.

The study's findings were used to shape homemade face mask recommendations here last April, with the comprehensive study findings published on March 22 in the journal Aerosol Science and Technology.

In all, the researchers tested 33 different commercially accessible materials not limited to cloth fabrics, including single-layer woven fabrics such as cotton and woven polyester, blended fabrics, nonwoven materials, cellulose-based materials, materials commonly found and used in hospitals, and various filter materials.

"We learned there was a lot of variability in filtration performance even in the same type of material," Ng said.

"We found commercially available materials that provide acceptable levels of submicron particle rejection while still maintaining air flow resistance similar to a surgical mask," said Ryan Lively, an associate professor and John H. Woody Faculty Fellow in the School of Chemical and Biomolecular Engineering. "These materials combine fabric fiber density, a maze-like structure, and fiber surface chemistry to effectively reject submicron particles."

The best-performing materials for homemade masks were blackout drapery and sterilization wrap widely used for packing surgical instruments. Both materials are commercially available.

The researchers said people should avoid using filters such as a HEPA/MERV or vacuum bags unless they are certified to be fiberglass-free since often such filters on their own may release glass fibers that can be inhaled. Other materials to avoid for masks include loose-knitted material, batting fabric, felt, fleece, or shiny, reusable shopping bags.

Multilayered samples performed much better than single-layer samples, but people should pay attention to breathability. The two-layered and three-layered samples tested show an overall filtration efficiency of about 50% for submicron particles. Mask fit is also important since particles can easily escape through gaps at the nose or through the sides of the mask.

The analysis showed that properly fitted and multilayer masks reject 84% of particles expelled by a person when one person wears it. Two people donning these types of masks reduces particle transmission by 96%.

A final takeaway of the research was the importance of universal mask wearing.

"The best way to protect ourselves and others is to reduce exhaled particles at the source, and the source is our face," Ng said, adding, "That really gets amplified when everyone starts wearing masks."

She expressed optimism that the findings will motivate people to more widely embrace mask wearing if they are sick and need to be in public.

"Not everyone understands the importance of airborne virus transmission, and the importance of wearing a mask," she said. "I hope that the practice will continue to help reduce the release of these viral particles into the environment and help protect others."


Georgia Institute of Technology

Journal reference:

Joo, T., et al. (2021) Evaluation of Particle Filtration Efficiency of Commercially Available Materials for Homemade Face Mask Usage. Aerosol Science and Technology. doi.org/10.1080/02786826.2021.1905149.
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