How Public Facemasking Can Reduce Virus Transmission By 91%

Why you should mask, plus patterns, materials, cultural change, and a shout-out to Betsy Ross.

Photo by Ani Kolleshi on Unsplash

The New York Times and Washington Post have now come around to a position I advocated for here on Medium last week: We should all be wearing masks. Not just health care workers, but ALL of us. Whenever we go out in public.


Because they work.

Research from the SARS outbreak in 2003 shows that washing hands 10+ times daily was 55% effective in stopping virus transmission; wearing a mask was actually more effective, reducing transmission by about 68%.

COVID-19 and SARS are similar types of viruses (coronaviruses), and it makes sense that what works to stop transmission for one will work to stop transmission of the other.

Masks work, first, because they are a physical barrier to whatever’s riding along on that air you’re breathing or moving through. Here’s a chart showing the relative barrier effectiveness for various materials:

At first I was excited to see this: Finally, a use for my old vacuum cleaner bags! Since then I’ve read that they are NOT a good choice because the filtering material contains tiny glass particles. So maybe use them to make coasters instead. :)

Secondly, they work because they keep you from touching your face all day long. The mask makes you more self-conscious of the fact that you’re not supposed to touch your face- specifically, your mouth, nose, and eyes, and the areas around them- and if you accidentally do, you’ll touch the mask, not your skin directly.

Third, the experience of other countries who mask show that masks work in the real world. In the words of Jeremy Howard, researcher and #Masks4All activist, explaining a chart in his recent Youtube video showing how some countries have successfully “flattened the curve” on new infections: “If you look at all the countries which have flat curves, they are countries where mask-wearing is extremely normal, and NOT wearing a mask in places like public transport would be considered anti-social.” He notes that the Czech Republic went from zero mask usage to 100% in 10 days, and in the process they halted the growth of new covid-19 cases. The Czechs made their own masks- the government didn’t give them out.

UPDATE: Jeremy Howard just published a fuller explanation of his views and research in a 3/29/20 Washington Post article. Among other things, he notes that the flaw in the current position of the US Surgeon General and the World Health Organization that only infected people should mask is that you don’t in fact know who IS infected. Because there is significant asymptomatic or presymptomatic infection, you yourself may be infected and not know it. The person who kindly holds the door open for you at the supermarket may be infected and not know it. As they said in the Czech Republic in their face mask campaign: “My mask protects you; your mask protects me.”

If you still need to be persuaded, take a look at this Chinese study of a local outbreak case on January 22 during the peak Lunar New Year travel season. A sick person on the bus who did not interact with anyone spread the virus to 7 others, some of whom were seated much more than 6 ft away. Two new passengers caught the virus 30 minutes after the original sick person had left the bus. NONE OF THE PEOPLE WEARING MASKS WERE INFECTED. Read the article, it’s very detailed, with a schematic of exactly where people were sitting on the bus.

So let’s say you’re convinced, and now you’re thinking of some kind of face covering. What are your options?

First, please don’t buy masks commercially, if by some miracle you could find them now. Commercially made PPE should be reserved for medical personnel at this time. Unfortunately, the shortage of commercially made PPE, and the lack of foresight that caused us to be in such a position of shortage, is probably why we initially got this messaging of “Masks don’t work!” They do, folks just didn’t want you to know it for a while, to avoid a run on masks. Think of the empty shelves in supermarkets across America where toilet paper used to live, and you understand why.

The easiest thing you can do to mask NOW are to use materials around the house. Get creative; anything that covers the mouth and nose and stays in place will work.

  • A turtleneck pulled up over your nose and mouth
  • A winter scarf or balaclava (What??)
  • A bandanna
  • A 5" stretchy yoga headband turned backwards
Me wearing my yoga headband backwards. And/or getting ready to knock over the 7–11.

Peter Tsai, who invented the technology behind N95 masks (the highest level of filtering masks in general use by medical personnel) recommends non-woven fabrics for your mask. Non-woven fabrics are bound together mechanically, thermally, or chemically, not woven like knits or cottons. Tsai recommends using car shop towels as mask material. They come in rolls and are usually blue in color. Per Tsai, they can be washed with soap and water and reused. Here’s a Youtube video for how to make one.

While it’s best if the mask fits well and there are no gaps between your face and the outside air, don’t give up on your homemade mask if you can’t achieve that. Any face covering will keep you from touching the skin around your nose and mouth directly, which may turn out to be the most important mechanism by which masks block virus transmission. If you inadvertently touch your face while you’re wearing a mask, you’ll just touch the mask, not your skin.

You can try to shape your face covering using pipe cleaners or opened-up rubber-coated paper clips in the part that goes over your nose to make a tighter fit — experiment. The most important thing is that you wash your hands, put on your face covering, and go out of the house protected.

And now we come to the gold standard of homemade masks- ones you sew yourself (or get a crafty friend to sew for you.) In the last few days a number of groups have formed to sew masks for medical personnel. Some of them sew for others as a way to earn money to make their masks for medical personnel. You can support them by ordering. Locally here in Baltimore we have a dry cleaner (if they offer tailoring services they also sew) from whom you can purchase hand-sewn cloth masks.

All of your masks should be of materials you can wash and dry. Use a fresh mask each time you go out, washing your hands before you put it on, then washing your hands when you walk in the door, then taking it off and throwing it in the hamper.

The simplest pattern is this one courtesy of my sister Ronnie Falcao, a renowned midwife in Mountain View, CA (and the wind beneath my wings for this article- she gave me multiple medical cites and urged me to do this). Her local hospital, Valley Med, was the first I’m aware of to request handmade masks from the public. Here’s a set of their instructions for a hand-sewn mask in its entirety:

If you have a sewing machine, there are a variety of patterns you can use- google it. Here’s one. Every day more videos are going up on Youtube on this subject- just search for “face mask sewing” online and you’ll find a ton. You can make different masks for different moods and different outfits.

Masks and photo by Teresa Linger, used by permission.

An advanced tutorial on what kind of mask to make is available courtesy of Cindy Rang of The Fabric Patch. Huge shout out to Cindi for her leadership on sewing cloth face masks and generosity in sewing for medical personnel. Her entire library of face mask videos is available at, and you can email her at with further questions.

If you’re sewing for yourself, please double your recipe, and make a mask for a health care worker. THANK YOU!

Betsy Ross, the Patron Saint of Patriotic Sewers

Ultimately, as time goes on, and more and more people adopt universal masking, commercial options will appear on the market again for purchase by non-medical personnel. As this change happens throughout the world, more companies will be making new and better products. You’ll have more choices.

But we’re not there yet. And so we come to the final part of this discussion, which is happening in your head today. You’re genuinely considering masking NOW. You’ve decided on what you’re going to use as a face covering. But you have concerns: How will it feel? Will it be awkward? What if I do it wrong? Will other people be willing to mask with me? You’re bummed because it’s less fun to bother with masking before leaving the house than it was in the old days, when you could just go out without having to think about putting one on.

Does this remind you of a national discussion we had decades ago about another virus, and what we were going to do about that? Yes, having sex with a condom is a pain in the ass, compared to having sex without a condom. And yet, we changed. We learned “No glove, no love.” And we can do the same here, for the same reasons: the health benefits are worth it.

Saving lives is worth it.

Helping the economy, which will do better the sooner we can ease the lockdown, is worth it.

Getting back to normal sooner, is worth it.

I just did an exchange with a friend who lives down the hall from me in my apartment building. I took some packages in for her; she has some weights I can borrow. We texted that I would leave the packages outside, text her, then she would pick them up, drop the weights, and text me. She would clear out and I would get the weights. It had all the charm of a drug deal. But we’ve learned to do it because we think our health, and the health of many, many people, some we care about, some we don’t know, depends on it.

Please, for all our sakes, consider adopting universal masking. Like you, I miss my friends, and the life we once had. Masking will help us all get back to it sooner, and will save lives. Please join me.

PPS: I’ve been asked to provide ideas for the 2 other elements of PPE that brought about that tantalizing 91% effectiveness in reducing transmission figure: gloves and gowning. Again, please leave the commercially-made products for medical personnel, who need it more. For gloves, you can check out restaurant and beauty salon supply houses, either online or brick-and-mortar. (This week alone I sourced 5000 exam gloves for 2 east coast hospitals from an online restaurant supply store.) Ask your local hospitals what they need you to get them in terms of exam gloves and order some for your local hospitals (not only is it the right thing to do, the doctor you glove may be your own); then, while you’re on the website, order standard food prep gloves for yourself. You’re not doing surgery, you’re just trying to keep your hands clean while you go about your grocery shopping, exercise, or helping homebound neighbors. You can protect yourself without cutting into the kind of PPE that medical personnel need.

For gowns, that just means whatever was your outermost layer when you went outside, you take that off and throw it in the dirty clothes hamper when you get home. You’ll be doing more laundry, but you’ll be healthier and safer for it. :) And take off your shoes at the door!

Stay safe & be well, Linda

*And for science folks, please click on this update on May 12, 2020 from a panel of scientists including Jeremy Howard, recommending universal mask-wearing to save lives and rescue the economy: “The preponderance of evidence indicates that mask wearing reduces the transmissibility per contact by reducing transmission of infected droplets in both laboratory and clinical contexts. Public mask wearing is most effective at stopping spread of the virus when compliance is high. The decreased transmissibility could substantially reduce the death toll and economic impact while the cost of the intervention is low. Thus we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies.”

EEOC Settlement judge; Mediator/investigator in sexual harassment/discrimination cases; US Presidential Scholar; Former appellate law clerk; Rabble-rouser

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