Face Coverings (Masks)


Before I dive into what I want to say, a reminder that until medical masks, including N95 respirators, are abundantly available, leave them for the health care workers and others on the frontlines. Even when they are available avoid N95s with exhaust valves. Also, face coverings/masks are to be used in conjunction with physical distancing and frequent handwashing.

The swiss cheese respiratory virus pandemic defense

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New Information as of 11–12–20

I wanted to put this update up front. When I first penned this missive, it was logical to assume that face coverings might help to protect the wearer, but the data was scarce. This article focuses on how face coverings protect others. But recently more data has come to light that face coverings also help to protect the wearer. Masks are a twofer. They protect others via source control and also help those that wear them.

“…Masks are primarily intended to reduce the emission of virus-laden droplets (“source control”), which is especially relevant for asymptomatic or presymptomatic infected wearers who feel well and may be unaware of their infectiousness to others, and who are estimated to account for more than 50% of transmissions.1,2 Masks also help reduce inhalation of these droplets by the wearer (“filtration for personal protection”). The community benefit of masking for SARS-CoV-2 control is due to the combination of these effects; individual prevention benefit increases with increasing numbers of people using masks consistently and correctly.”

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New recommendation as of 12–30–21

With the recently identified Omicron variant there is a push to upgrade our masks. Properly constructed cloth masks are good, surgical masks are better, and N/K 95 masks are best.

Health officials and experts are increasingly saying it’s time to upgrade your face masks, especially in light of the Omicron surge.

California’s public health director and health officer, Dr. Tomás Aragón, wrote recently that with the increasing airborne spread of the coronavirus, it’s important to improve the fit of masks and their filtration — making enhancements that go beyond old, loose, cloth face coverings that became popular in 2020.

Dr. Robert Wachter, chair of UC San Francisco’s Department of Medicine, agreed. Since Omicron is twice as infectious, Wachter wrote, “an encounter that you could have tolerated for Delta may well infect you [with] Omicron. Knowing this, it’s worth upgrading the protection you get from your mask.”

Effectiveness of Face Mask or Respirator Use in Indoor Public Settings for Prevention of SARS-CoV-2 Infection

Now back to the regularly scheduled article.

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One of the insidious things about COVID-19 is that people can give other people the disease without knowing it. This is called asymptomatic or presymptomatic transmission. You or I could be walking around exhaling virus laden droplets and not even know it. Some that exhale viral droplets will never show symptoms, this is being asymptomatic. Others will be exhaling viral droplets before they get visibly sick, that is being presymptomatic. This is where masks/face coverings come into play, especially as we reopen and interact more in the community.

I’m not sure why there are any issues with wearing face coverings. Initially they can be annoying, but you get used to them. It is also obvious that they can help, and you don’t need to be a scientist to understand why. Imagine you are walking around unknowingly exhaling virus laded droplets every time you breath or talk. There is nothing restricting them from projecting out into the environment. Now put on a face covering. Your exhalation is restricted. It won’t be traveling as far. If you wear glasses, you can literally see and feel it. The glasses get fogged as you feel your breath being contained near your face. Then if you wear a mask for a little while and remove it, you’ll notice that the inside is a little moist. That is from all the droplets trapped in the fabric. Every droplet caught is one less potentially virus laden droplet out in the world. Cloth face coverings/masks are not perfect, as shown by the glasses fogging, but they do reduce how far the droplets travel should they wind their way through or around the mask. Additionally, masks trap droplets within their fabric. You can see how that works just by wearing one.

While new data keeps coming in support of the obvious, the prior data was enough for the CDC, FDA and the European Centre For Disease Prevention and Control to support using face coverings. Which leads me to wonder about a Venn Diagram consisting of people who yell about funding research into the obvious as wasted money and people yelling to see research on if masks can restrict the flow of respiratory droplets when we breath. By how strong my irony senses are tingling, I think there might be a large overlap 😉. Just to be clear, I’m in favor of more research along these lines, even if the overall concept is obvious.

Recently the Data Evaluation and Learning for Viral Epidemics group from The Royal Society looked at the issue and came away with same conclusion as the above agencies, as well as Health Canada. The president of The Royal Society was pretty clear on the topic:

“In the case of COVID-19, we know that you can be infectious even when you do not have any symptoms. We know that coughing, sneezing, and even talking or breathing release droplets from the mouth that are a key means by which the virus spreads. We also know that cloth-based face masks reduce the spread of those droplets.”

This excerpt from an article in The Conversation sums it up nicely:

“Given all of the laboratory and epidemiological evidence, the low cost of wearing masks — which can be made at home with no tools — and the potential to slow COVID-19 transmission with widescale use, policymakers should ensure that everyone wears a mask in public.”

The WHO has also joined the club.

At a press briefing on June 5, WHO Director-General Dr. Tedros Adhanom Ghebreyesus announced that the organization now recommends people who live in areas experiencing “widespread transmission” of COVID-19 wear a fabric mask whenever social distancing of at least one meter (about three feet) is not possible. The guidance applies even to those not showing symptoms of coronavirus, as research now strongly suggests many people with the disease are asymptomatic or only mildly symptomatic.

I do have some thoughts on where the more understandable* push back on masks comes from. One comes from a bias and the other from what I see as an overblown concern. When we think of masks, a lot of us only view them as protecting ourselves, probably because that is how they are used in medical settings while taking care of infectious patients and on TV medical shows. That bias is hard to shake. I may have had a leg up on viewing this differently since I worked in cell culture. The only reason I wore a mask on the job was to protect the cultures from me, not the other way around. Cloth face coverings/masks are not to protect us, they are to protect others from us as I outlined above. Unfortunately, they are a poor means of self-protection (see my update at the top of the article), and many of the concerns that arise from their use don’t really take that into consideration.

Reducing transmission of SARS-CoV-2

Imagine you are out in the wilds and wearing your mask/face covering. You encounter a friend who doesn’t have a mask. Neither of you are aware that your friend is infected and is exhaling virus laden droplets. You stop to chat and move closer than the suggested physical distancing requires for your brief conversation. As you are chatting, each exhalation from your friend sends droplets your way. Over time the outside of your mask gets a viral load large enough to be infectious. By then it is too late, you are infected. That is because the droplets are not just hitting your mask but your whole face. An infectious load has made it to your eyes, some may have come around your mask as you inhaled, and others may have even wound their way through the mask. Now imagine the same situation but your friend also has a mask. It will take much longer for an infectious load to get to you, if at all, as the pathway to you is restricted by your friend’s mask. Your brief conversation wasn’t enough to expose you to an infectious load, because your friend had a mask. You and your friend were thinking about others, even if you blew it on physical distancing.

The bias on thinking of the mask as only protecting the wearer raises concerns of self-contamination because the assumption is that the mask protected you but in doing so it may have acquired enough infectious viral particles on the outside of the mask to make you sick. That means you can transfer them to you by fiddling with the mask too much or forgetting handwashing steps when removing it. If you do that you can transfer an infectious number of viral particles from your mask to your hands and then to your face. Odds are if your mask/face covering is contaminated enough to be infectious, you were already exposed through your eyes with an assist from the infectious particles breathed in or around the mask. The self-contamination concern is largely moot at that point. You could still have a sub-infectious number of viral particles on your mask, so be sure to take all appropriate precautions. I’m not suggesting it is ok to be carless with the mask, just that the concerns about being careless as a justification for not using masks isn’t really valid. Even if it was, that is an education on the use of masks problem, not a reason to abandon them.

The other issue is that a mask might make a wearer overconfident and forgo physical distancing. I hope my example of an imaginary chat with a friend helped to reinforce that masks are to be used in conjunction with physical distancing.

If we all wear masks out in the community it can help reduce the spread of COVID-19. It isn’t a panacea, but to be used with physical distancing and hand washing. It is of primary importance in places where physical distancing is problematic. If everyone is masked, people are trapping their droplets in their masks and containing their droplets closer to their vicinity. This creates a much smaller potential zone for infecting others which is key when physical distancing isn’t easy to maintain. It gives you more time to get in and get out even if you pass near people. Remember, infection consists of both exposure, and the time that you are exposed. Masks can help with that equation.

I’ll finish with one way that a cloth mask can really protect you. It is more emotional than physical protection. Contact tracing will soon be part of our reality going forward. I know that if I was unknowingly infected and went out unmasked, encountered people, and their subsequent illnesses was traced back to me, I’d be regretting my decision to not wear a mask, especially if someone got seriously ill or worse. I wouldn’t want that on my conscience. Which is another reason why I will wear my mask if I’m going to a place where there is even a hint that physical distancing may not be possible. I hope you will too.

Dr. Hall illustrates the gas exchange in these photos. I spoke with her, and the exhaust valve of the N95 mask is taped shut from the inside so she is keeping her respiratory droplets contained. Here is her post and a story regarding that post.
  • The less understandable issues of rebreathing CO2 or inhaling some of your exhaled virus particles makes little sense. CO2 consists of 3 atoms, O2 of two. Those atoms passing through N95 respirator masks are not an issue for gas exchange, so a cloth face covering that can’t be tightly sealed to your face isn’t going to be a problem. Neither are a few viral particles that just came from your site of infection getting sucked back in. It won’t make you sicker than you already are.

Update: SciMoms just (7/27/20) put out a great FAQ on masks. I think it pairs well my missive, so I thought I’d highlight it here:

SciMoms COVID FAQs: Do masks slow the spread of COVID-19?

Author Unknown


What is a mask valve, and why are cities banning them?

Omicron surge means it’s time to upgrade your mask. Here’s how

Effectiveness of Face Mask or Respirator Use in Indoor Public Settings for Prevention of SARS-CoV-2 Infection — California, February–December 2021

Scientific Brief: Community Use of Cloth Masks to Control the Spread of SARS-CoV-2

CDC: Evidence supports SARS-CoV-2 transmission while presymptomatic or asymptomatic:

Use of Cloth Face Coverings to Help Slow the Spread of COVID-19:

FAQs on the Emergency Use Authorization for Face Masks (Non-Surgical):

Using face masks in the community:


DELVE group publishes evidence paper on the use of face masks in tackling Coronavirus (COVID-19) pandemic:

It’s now recommended that Canadians wear face masks:

Following the science:

Masks help stop the spread of coronavirus — the science is simple and I’m one of 100 experts urging governors to require public mask-wearing:

Coronavirus disease (COVID-19) advice for the public: When and how to use masks

Anyone Living in Areas With ‘Widespread’ COVID-19 Transmission Should Wear Masks, WHO Says

Reducing transmission of SARS-CoV-2

How to put on, use, take off and dispose of a mask:


Staying safe isn’t just about hygiene and distance. It’s about time, too:

Contact Tracing:


Wearing face masks does not cause hypercapnia or affect the immune system:

False health claims circulate about wearing masks during pandemic:

Moving Personal Protective Equipment Into the Community:



In this section I will post updated information on face coverings/masks as I run across it.

Face Masks Considerably Reduce COVID-19 Cases in Germany:
A Synthetic Control Method Approach: http://ftp.iza.org/dp13319.pdf

Identifying airborne transmission as the dominant route for the spread of COVID-19:

A modelling framework to assess the likely effectiveness of facemasks in combination with ‘lock-down’ in managing the COVID-19 pandemic:

Physical Distancing, Face Masks, and Eye Protection to Prevent Person-To-Person Transmission of SARS-CoV-2 and COVID-19: A Systematic Review and Meta-Analysis:

Visualizing the effectiveness of face masks in obstructing respiratory jets:


The president of The Royal Society speaks to more evidence on face coverings.

Universal use of face masks for success against COVID-19: evidence and implications for prevention policies

Absence of Apparent Transmission of SARS-CoV-2 from Two Stylists After Exposure at a Hair Salon with a Universal Face Covering Policy — Springfield, Missouri, May 2020


From the AMA: The 6 things doctors wish patients knew about masks

Face Coverings Could Save 130,000 American Lives from COVID-19 by March

Masks Work. Really. We’ll Show You How

Face masks effectively limit the probability of SARS-CoV-2 transmission

Masks & Face Coverings for the Public

One last thing.

Since you scrolled past the references and postcript, here is my other final thought 😊. What I’m looking forward to seeing is research on Face Shields. I think they might be protective for the wearer and perhaps to others, seeing as how it covers the whole face. As this pandemic continues, I think we’ll get an answer. This paper is a good start, “Moving Personal Protective Equipment Into the Community”:

“To minimize the medical and economic consequences, it is important to rapidly assess and adopt a containment intervention bundle that drives transmissibility to manageable levels. Face shields, which can be quickly and affordably produced and distributed, should be included as part of strategies to safely and significantly reduce transmission in the community setting. Now is the time for adoption of this practical intervention.”




Microbiologist who has worked with both mammalian and bacterial cells. Now I follow science via my Eclectic Science page. www.facebook.com/EclecticScience/

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Eclectic Science

Eclectic Science

Microbiologist who has worked with both mammalian and bacterial cells. Now I follow science via my Eclectic Science page. www.facebook.com/EclecticScience/

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