CATER Mask Decisions

January 19, 2021


Join Us on Thursday to Debate the Mask Issues

Media Supply will be Substantial According to Dave Rousse

Mobile Device to Insure Selection of the Mask with the Right Fit

Leveraging ASTM Label Initiative for Efficient Public Masks

Breathing Resistance, Filtration Efficiency and Media Area

FFP 2 Masks Now Required in Retail Stores and Public Transport in Austria and Germany

FFP 2 is Close to N95 in Performance

NC State Working on Reliable Ways to Test Mask Effectiveness

Everyone in Singapore Wears Efficient Masks Why Not in the U.S. and ROW?


Join Us on Thursday to Debate the Mask Issues

We anticipate a lively discussion Thursday at 10AM Central Time to discuss if and how tight fitting and efficient masks should be quickly supplied to everyone.  

In this Alert you will see summaries of comments which will be made by some of the participants.

This Alert also has coverage of countries which already are requiring tight fitting, efficient masks in public space. So the discussion is not about whether some country should do it but whether other countries should follow suite.

The major relevant issues to be individually debated are:

·         How efficient will tight fitting efficient masks be in capturing and preventing the spread of the virus?

·         Can sufficient numbers of tight fitting efficient masks be made available to have the short term impact?

·         Is the tight-fitting mask needed when vaccines will soon provide herd immunity?

·         Are masks the most cost effective option?

Subsidiary and clarifying subjects are:

·         What is the definition of tight fitting and efficient?

·         What efficiency level should be required?

·         How do you measure air leakage?

·         Who measures air leakage?

·         How long can the mask be used before cleaning?

o   What cleaning procedure should be utilized?

o   What will be the impact on effectiveness  as a result of cleaning?

To register for the webinar click here:

Media Supply will be Substantial According to Dave Rousse

Dave Rousse, President of INDA will be participating in the webinar on Thursday and can answer questions about media supply.  He provided the following summary.

“INDA tracked 34 new Meltblown production lines, through announcements and/or industry contacts, that were to be installed and operating by end of 2021. Since starting this tracking, the likelihood of five lines has softened, perhaps due to fears of overcapacity. Nevertheless, we see 16 of these lines capable of the fine-fiber, electrostatically charged media that goes into high performance facemasks.

“We see US N95 respirator production moving up to 274 million/month from 42 m/m in early 2020. Combined respirator and medical facemask production would require about 9500 tonnes of fine-fiber, electrostatically charged meltblown per year. We appear to have that covered with current investments, and capacity available as well to either make ASTM Level 1 or 2 masks, and filtration media to meet MERV 12 or14 requirements. 

The tightness is moving to spunbond.

As to the ASTM performance standard, still moving through the balloting process, it does attempt to establish MINIMUM performance levels (20% and 50%) for filtration efficiency (using the N95 test method, different pass/fail criteria) and for comfort, as measured by pressure drop. The higher performance level, ASTM Level 2, requires a minimum 50% filtration efficiency and maximum 5 mm H2O pressure drop. It is the latter requirement (pressure drop) that will be the most challenging to achieve at higher efficiency levels. It may require designing media to the 5 mm pressure drop and then solving for the filtration efficiency, which would range from 50% to the highest we have seen, which is 96% at this level.”


Mobile Device to Insure Selection of the Mask with the Right Fit











Keith Dellagrotta will be participating Thursday to talk about a very interesting use of mobile devices to insure the selection of the best fitting mask.

M^ is a Silicon Valley tech startup that leverages advanced 3D vision and analytics to perform high fidelity anatomical scans using a mobile device. Relevant to the COVID-19 pandemic, the company produces an iPhone app with which users can take a “selfie” and then, using photometric and AI technology, the app converts the picture to a reliable 3D digital model, stored locally on the personal phone. This model allows prediction of how a mask will lie on an individual’s face.


M^ recently teamed up with Vogmask to help customers make educated and confident online shopping choices with the app regarding which mask size to buy without having to physically try it on. Additionally, the deidentified scan calculations can assist in future mask design iterations by providing information on the variance and mean facial measurements of customers.


Originally My Mask Movement, the company was founded to help address the shortage of PPE at the start of the pandemic by creating custom-fitted, 3D printed N95 masks. The underlying core IP that facilitated creation of the personalized masks evolved into the company’s current capabilities. They still continue to donate respirators to individuals in need according to their mission to save as many lives as fast as possible.



Leveraging ASTM Label Initiative for Efficient Public Masks

Erick Couch will participate on Thursday and chart a course for public acceptance of more efficient masks using the ASTM label as a major selection criterion.

Eric  believes a power point presentation which is viewed at

provides a  meaningful depiction that can be comprehended by the general public...illustrated ranges with indicators for performance of N95s, cloth face.

      ASTM  – Respected Industrial Standard Body


      Allows use of widely available materials that provide high performance filtration without impacting N95 supply to frontline responders.

      New and Existing Mask Fabricators Can Scale Supply within 6 Weeks

      Performance Measures

      Sub-micron Particle Filtration (i.e. 95%)


      Inward Leakage Assessment

      Eliminates Lengthy Testing / Approval Process

      Chaired by CDC Deputy Director Jonathan Szalajda

      Impact: Immediately contrasts surgical and cottage industry non-sealing masks with a high performing masks made to measurable standard.

       Jan 4 Vote            Jan 12 Special Meeting           Feb 12 Release

      NOTE: Establishes measurement method, defines ranges.

      Exact performance of a point design can vary within the range.



Erick shared the following thoughts  “I have had to emphasize with both Biden’s team as well as the Aerosol Experts that in fact the standard is a “Measurement Framework” that provides “ranges” (20-50, 50-100). It does not specify performance levels needed for any use case. 

“We should adopt a different way of referring to the ASTM standard going forward.:  ASTM @ Filtration XX, Breathability YY, and FIT ZZ . Why is this important ?  

“There is already too much confusion regarding mask assertions. The public message needs to be concise, consistent, and comprehensible by the general public. Social science research has found that more than three elements that require choice results in confusion. 


“I am a fan of your use of CATER to calibrate interested parties to all aspects of mask design. This is very important to the mask advocacy community, however I would not recommend putting this to the general public as this is altogether a different construct. I believe we will be pushing the envelope just to get them to understand there is a new standard and they should make decisions based on the three primary factors. 

“I also appreciate FFE as a simplification, yet as you noted, fit and filtration are independent. For this reason, I still come back to the public messaging...that the simplest we can achieve is “ ASTM @ Filtration XX, Breathability YY, and FIT ZZ”. 

“As an aside, I’ll share my thoughts on Level 1 and Level 2. While the standard defined Level 1 and Level 2, I find these constructs not helpful since there are only three true figures of merit: filtration, breathability, and fit. Levels seem to be only an abstraction and given the confusion, unnecessary added complexity should be avoided. 


Breathing Resistance, Filtration Efficiency and Media Area

McIlvaine would like to see more data on the relationship between media area and resistance or breathability. Resistance rises as the square of the velocity. If the resistance is 16 ” mm H2O. and then you double the amount of media the resistance drops to 4 mm  H2O.  Conversely if we are disqualifying a media with 7 mm H2O  and want to reduce it to 5 mm we only have to make a small increase in filtration area.

Another factor is leakage. If half the air is leaking around the mask the resistance is only ¼ of what it would be with a tight fit

Erick Couch talks about keeping things simple for the purchaser. That is good advice. But the designers and regulators need to keep the velocity vs resistance formula in mind. Dave Rousse talks about designing the media first around the 5 mm H20. Just designing the mask with more media should be one of the variables to consider.

One of the design options might be an internal brace. A small extension would substantially increase the media area.


FFP 2 Masks Now Required in Retail Stores and Public Transport in Austria and Germany

FFP2 masks will now be required in all retail shops and supermarkets, along with public transport throughout Austria. 

Previously, cotton masks or scarves were sufficient to satisfy the regulation. 

Austria put in place a range of stricter rules after a meeting on January 17th, including extending the lockdown until February 7th. 

While FFP2 masks are more expensive than standard medical masks, the government has promised that they will be available to Austrians at cost price. 

People on low incomes would be entitled to the masks for free, a government spokesperson said. 

Supermarkets Lidl, Spar and Rewe told APA on Sunday that they would be selling the masks at cost price - although they were unable to confirm the exact costs of the masks on Sunday. 

A spokesperson from Rewe told Der Standard that the masks would be offered “as cheaply as possible”. 

The retailers also indicated that there would be no issues with supply, even as demand is set to spike as a result of the new law. 

“Any mouth and nose protection is good, but the FFP2 mask is massively better," said Health Minister Rudolf Anschober (Greens) on Sunday. FFP2 masks offer better protection against the coronavirus and other pathogens, with up to 94 percent of aerosols filtered out. 

Germany is weighing up following Austria and Bavaria’s lead in making it compulsory to wear full protective filter masks on public transport and in shops, as the country remains on high alert about the impact of possible coronavirus mutations.

In Germany’s largest and southernmost state, Bavaria, a similar requirement for trains, trams, buses and supermarkets came into force on Monday, though the new rule will not be policed until 24 January and allows for exemptions for bus drivers, ticket inspectors and children under the age of 15.

When fitted properly, FFP2 masks promise to filter out at least 94% of particles but are also more expensive, usually retailing at between €2 and €5 per mask. If FFP2 masks were made mandatory before suppliers are unable to meet the new demand, prices are expected to rise further. Some virologists warn a new compulsory mask rule could end up being counterproductive.

“In theory, the move to more professional masks is welcome,” said Jonas Schmidt-Chanasit, a German virologist and Professor of Arbovirology at the University of Hamburg. “But I’d be wary of simply copying the Bavarian model without considering the possible downsides.

“In most cases FFP2 masks will be ineffective if they aren’t professionally fitted: people will end up breathing through the gap between mask and face rather than through the designated filter.” Virologists also say that beards can prevent the masks from sealing properly around the face.

“I can see how FFP2 masks could be a useful emergency solution for workplaces where you cannot easily guarantee safety ventilation,” Schmidt-Chanasitsaid. “But I am skeptical of making them mandatory on public transport, where there are other ways to avoid the risk of aerosols, and where passengers may be forced to wear masks for longer than the 75 minutes advised by regulatory authorities.”

Andreas Podbielski, director of Rostock University’s Institute of Medical Microbiology, Virology and Hygiene, described the new mask requirement at “populism and nonsense”. “I don’t see a gain in safety but plenty of risks,” he told Munich’s Abendzeitung newspaper.

Questions around the availability of FFP2 masks, which are equivalent to N95 filtering facepiece masks in the United States and the KN95 standard in China, have also yet to be answered.

In Germany, the government has since 15 December sent out vouchers for FFP2 masks to 34.1 million citizens aged over 60 or with a history of illness such as cancer, with the aim of supplying 15 masks to every person in that category before the end of January.

A spokesperson for the Federal Union of German Associations of Pharmacists said its members had so far coped well with the demands of this trial run. “But to supply filter masks to 80 million people, that’s a different challenge. I wouldn’t want to speculate on the outcome.”

While some German suppliers have started to specialize in manufacturing FFP2 respirators, the bulk of masks is made in China and can take up to four weeks to deliver.

Germany’s disease control agency, the Robert Koch Institute, on Monday reported 7,141 new infections in the last 24 hours, the lowest rate since 20 October. “After a sharp increase in the number of cases at the beginning of December, a decrease during the holidays and a renewed increase in the first week of January, the number of cases seems to be stabilizing again,” the RKI wrote in its report on Sunday evening.

But Germany remains well below its stated target of 50 new infections per 100,000 inhabitants within the space of seven days, in spite of several weeks of restrictions. “The numbers need to come down further,” the health minister, Jens Spahn, said on Monday.


FFP 2 is Close to N95 in Performance

Europe uses two different standards. The “filtering face piece” score (FFP) comes from EN standard 149:2001. Then EN 143 standard covers P1/P2/P3 ratings. Both standards are maintained by CEN (European Committee for Standardization).

Let’s see how all the different standards compare:

Respirator Standard

Filter Capacity (removes x% of all particles that are 0.3 microns in diameter or larger)

FFP1 & P1

At least 80%

FFP2 & P2

At least 94%


At least 95%

N99 & FFP3

At least 99%


At least 99.95%


At least 99.97%

As you can see, the closest European equivalent to N95 are FFP2 / P2 rated respirators, which are rated at 94%, compared to the 95% of N95.


NC State Working on Reliable Ways to Test Mask Effectiveness

Researchers at the North Carolina State University Textile Protection and Comfort Center are working on consistent and reliable ways to test the effectiveness of cloth face masks used by the public to limit the spread of the coronavirus, building on their expertise in testing protective equipment for firefighters and first responders. The NC State News Abstract interviewed one of these researchers.

“In March, we saw that people were making cloth masks, and we realized there were no specifications or consistent testing for them,” said Bryan Ormond, assistant professor of textile engineering and chemistry in the NC State Wilson College of Textiles. “We started looking at: How do we look at making better tests?”

The Center for Disease Control and Prevention recommends the general public wear multi-layer cloth masks to prevent transmission of SARS-CoV-2, the virus that causes COVID-19, by reducing spread of the virus through respiratory droplets as well as to reduce inhalation of droplets by the wearer.

To learn about strides in testing cloth face masks, the Abstract sat down with Ormond to talk about research into testing cloth masks for the public, which are considered the last line of defense against the spread of the coronavirus.

The NC State News Abstract: Can you describe some of the tests you’re doing on face masks worn by the general public?

Ormond: We worked during the pandemic at our homes, some in the lab, to put together a couple tests to be able to just get a screening level using ambient air particles. We wanted to see how well the materials filter.

We essentially put fabric in a cell, passed air through it and counted the particles on either side. That gives us an idea of the filtration efficiency. We recently added an aerosol generator to give us a consistent level of particles at a consistent size because you can’t really control ambient air from day to day.

The other approach is to look at the full product. When you make a cloth face covering, it is not a flat piece of material. It has the openings around the face, the nose. It has a fit factor that also affects the performance.

We have an animatronic breathing head form that we can control. Testing masks on our articulated head form allows us to simultaneously get a measure of filtration efficiency and fit.

TA: How do cloth face masks protect people?

Ormond: Any time you’re dealing with some sort of hazard you’re trying to protect people from, you look at this hierarchy of strategies for how you can control the hazard. Typically, you’re starting with administrative and engineering controls. In this case, that refers to keeping six feet of distance, washing your hands and staying at home – those are going to separate you from the hazard.

The PPE, the respirators and the face coverings are a last line of defense in any situation, not just in respiratory protection.

The other is this idea of getting everyone to realize that a mask, a face covering is just one of the tools that we can use. It’s a public health strategy. Every single person wearing a mask just cuts things down a little bit from spreading.

TA: Are there standards for cloth face masks?

Ormond: Right now there is no certification process or specification for cloth face coverings for the general public. The American Association of Textile Chemists and Colorists, AATCC, came out with a design specification or guideline on how to construct them.

Now, a task group of ASTM International’s subcommittee on respiratory protection – with experts from around the country – is coming together to put together a specification. That involves setting design and performance requirements so every mask can be certified through a process. We also have to pick the correct test methods that provide relevant performance to the use conditions.

TA: What do you look for in a face mask?

Ormond: There are three main performance characteristics you want to look at. One of those is filtration efficiency. If you pass air with particles through that fabric, how many particles does that fabric actually stop?

The next thing that you want to look at is breathability. Filtration and breathability typically have an inverse relationship, so as you increase the filtration performance, the material or composite becomes less breathable. So the balance between these two is critical for an effective face covering.

The last one that’s most important for providing any protection to the wearer is the fit. If the mask doesn’t fit and seal to the face, you can have the best filtration material possible, it can block everything in a material level test, but if you put it on your face, what’s going to happen is the air you’re breathing in is actually going to follow what we call a “path of least resistance” and move around the material instead of through it. This is less of a concern if you are intending the face covering to only function as a means to limit spread and protect others from the wearer.

TA: What’s your ultimate goal for face mask testing?

Ormond: We want to be able to develop a rating system. Right now a regular person shopping for a mask is looking at four, five different masks, and has no real way of comparing those. If you have a specification in place, you at least know that these have been through a process, that they have been tested, shown to work to some level that has been agreed upon by a group of experts.

The other thing you could do is you can show how one varies in breathability or material filtration. What you want to have is to get a measurement or a rating of how breathable something is so people can make an informed decision.

A YouTube presentation on the mask testing work is found at


Everyone in Singapore Wears Efficient Masks Why Not in the U.S. and ROW?

Zeynep Tufekci and Jeremy Howard have a new article in the Atlantic posing the question of why we are still not wearing efficient masks.  It is based on a previous paper.

“We first released the paper as a preprint back in April, and it took nine months to go through peer review. We’re happy that it’s published but, to be honest, we’re also deeply disappointed that it’s still relevant. We’d hoped that by 2021 supply chains would have ramped up enough to ensure that everyone had better masks. Cloth masks, especially homemade ones, were supposed to be a stopgap measure. Why are so many of us still wearing them?

“Don’t get us wrong; everything we said about the efficacy of cloth masks stands the test of time. Wearing them is much better than wearing nothing. They definitely help reduce transmission of the coronavirus from the wearer and likely protect the wearer to some degree as well. But we know that not all masks are equal, and early on in the pandemic, there was a dire shortage of higher-grade masks for medical workers. During those emergency conditions, something was much better than nothing. There are better possibilities now, but they require action and guidance by the authorities.

Even all cloth masks are not equal. Construction, materials, and fit matter, and these can’t be tracked or certified with homemade masks. Unlike cloth masks, medical-grade masks (also called respirators) that adhere to standards such as N95 (in the U.S.), FFP2 (in the European Union), and KN95 (in China) do a much better job of protecting the wearer and dampening transmission. Ideally, they should also come with instructions on how to wear them and ensure that they fit properly.

“Because we have written about masks, we’ve become informal advisers to friends, family, and strangers on the internet. We’re not much help, though. When our friends ask us simple questions like “Where should I buy a mask?” or “Is my mask any good?,” we don’t have great answers. We can mumble generalities: Make sure it fits wellhere are some guidelines about layerstry to avoid fake N95s. But if we can’t give wholly satisfying answers to such basic questions, then how is the general public expected to fare?

“Tragically, America is swamped with fraudulent medical-grade masks, some of which are only 1 percent effective. Many masks do not have labels clearly indicating their manufacturer. Some official mask-testing methods are inappropriate, including the use of far higher pressure than normal breathing exerts. No reasonable certification is available for the most useful masks generally available to the public. All of this means that everyone has to somehow figure out for themselves which masks are effective.

“We routinely get PR pitches for excellent new solutions as well as snake-oil remedies, and we sometimes have trouble telling them apart—how is an ordinary person supposed to evaluate competing claims? When we share our articles about masks on social media, we are asked where to buy proper masks. Not only do we have no answer, but we often find that marketers will answer instead, directing readers to unreliable, overpriced masks. Worse, the supply situation apparently remains so dire that the CDC still “does not recommend that the general public wear N95 respirators,” because they’re crucial supplies that must continue to be reserved for health-care workers and other first responders.

“Not all countries have this problem. Taiwan massively scaled up its manufacturing of masks at the start of 2020, such that by April every citizen received a fresh supply of high-quality masks each week, and the distribution system was regulated by the government. Taiwan’s COVID-19 death rate per capita is more than 1,000 times lower than that in the U.S. Hong Kong has been distributing patented six-layer masks (the efficacy of which has been laboratory tested) to every citizen. Singapore is on at least its fourth round of distributing free, reusable, multilayer masks with filters to everyone—even kids, who get kid-size ones. In Germany, Bavaria has just announced that it will be requiring higher-grade masks. If all of these places can do this, why can’t we?

Fixing this problem is more urgent now that a new variant of the coronavirus, known as the B.1.1.7 lineage, is making its way around the world. This variant is believed to be about 50 to 70 percent more transmissible than earlier strains of the virus. Masks are an important part of the battle against this new variant because they decrease transmission by reducing the number of infectious particles spread by a mask wearer (known as “source control”) and by reducing the amount that a mask wearer inhales. The cloth masks that we focus on in our paper do a good job at source control, but on their own they do not protect the wearer as well as medical-grade respirators do. That’s why health-care workers wear respirators, and that’s why leaving existing supplies for them was important early on—they were dealing directly with COVID-19 patients, so they needed the protection. Right now, while the CDC language on supply shortages has not been updated, it’s unclear if that’s because the shortages are really that dire or because this topic has not been paid sufficient attention. In either case, the CDC should update us on the situation. And if, indeed, we are still suffering from shortages, emergency measures should finally be implemented to manufacture such masks at home.

Not having higher-grade medical masks or even reliable, certified cloth masks distributed to the population means more transmission. But that’s not all. If we could confidently tell people that the masks would also help protect the wearer from infection, we would likely get more people to wear them. Appealing to solidarity is excellent (“My mask protects you; your mask protects me”) but being able to confidently add self-interest to the equation would be even better.

Ideally we would have ramped up supply and been able to produce and distribute certified higher-filtration masks to the whole population. At a minimum, we should have created a certification program and a distribution channel that allows people to purchase higher-grade masks with confidence. Even better, we could have distributed them to the public for free like so many other places. It’s not just that many other countries showed us the way: Many experts have been urging a switch to better-grade masks as soon as possible. For example, Abraar Karan and his co-authors wrote on the same topic many, many times, in May, June, October, and even this month. As Karan pointed out to us, the fact that some people refuse to wear masks makes it even more imperative that we distribute higher-grade masks to those willing to wear them.

We need the CDC and the FDA to step up and provide simple, clear, actionable, and specific information that would allow the public to know which masks are reliable and where they can get them, as well as how to upgrade and better wear their existing options. Initial studies suggest that widely available surgical masks, combined with a mask brace, could increase the effectiveness of the surgical masks. Cloth masks can be upgraded with a nose wire (for fit) and a filter insert—and more than 100,000 types of these masks are available on Etsy. A good supply of KN95 masks is available from China, with many supermarkets and pharmacies now selling them for a couple of dollars each. But none of these solutions can work widely as long as the public has little guidance on which masks are reliable and certified.