It’s a no-brainer, so much so that the Internet is teeming with arguments lately encouraging mask-wearing in public until the pandemic is over. The CDC is reportedly weighing whether to formally recommend it, as Ed will detail in an upcoming post.

I’m even inclined to agree with Tucker’s theory for why the feds have discouraged mask-wearing to this point. It’s not because masks don’t work. They do. It’s because the shortage of masks for medical professionals is/was so severe that the CDC feared public demand would overwhelm the already scant existing supply if Americans were suddenly told to cover up. Every mask that hasn’t been bought and hoarded by an average joe is a mask that’s available to a doctor, nurse, or EMT.

But it’s not a zero-sum game, of course. As Carlson says, no one disputes that medical workers should have priority for top-of-the-line N95 respirators. The question is whether we should be making our own basic cloth masks to provide some minimal protection in public to reduce levels of transmission. Answer: Obviously. They work!

My data-focused research institute, fast.ai, has found 34 scientific papers indicating basic masks can be effective in reducing virus transmission in public — and not a single paper that shows clear evidence that they cannot… Studies have documented definitively that in controlled environments like airplanes, people with masks rarely infect others and rarely become infected themselves, while those without masks more easily infect others or become infected themselves… Oxford University found evidence this month for the effectiveness of simple fabric mouth and nose covers to be so compelling they now are officially acceptable for use in a hospital in many situations.

A 2013 study looked at the best widely available materials for filtering out tiny droplets that might carry a virus from one person to another. It found that cotton fabric available in t-shirts or pillowcases were 68-70 percent effective compared to the 89 percent effectiveness of surgical masks. More layers are better, although obviously that’ll reduce breathability, and a snug fit is essential. Per Business Insider, a 2006 experiment found that an effective mask providing “substantial protection” could be made without sewing: “First, they boiled the cotton for 10 minutes to sterilize it, then cut it to size and formed a mask using one outer layer and eight inner layers covering the nose and mouth. The mask could be tied around the head to get a snug fit without elastic.”

The more of us who wear masks, the more layers of filtration there are between each of us and the virus. A biologist published a post a few days ago at Medium noting that a tea towel worn around the mouth and nose will reduce particles in the near atmosphere produced by coughing by 10 percent; the same tea towel worn by someone in the vicinity should catch two-thirds of the particles that make it through the cougher’s mask. (Results were much better with surgical masks and N95s.) Droplets can spread from an infected person to the uninfected even without coughing or sneezing, of course, but coughing or sneezing ejects them so rapidly that particles can reach much further than the standard six-foot radius recommended as part of normal social distancing. Masks are a last line of defense around a symptomatic person.

In lieu of N95s, surgical masks seem to be the best option…

Similarly, in a study still under review, 246 participants with symptoms of respiratory infection breathed into a droplet-collecting device called the Gesundheit-II for 30 minutes. When volunteers were bare-mouthed, coronavirus was detected in 30 to 40 percent of their sampled droplets; when they wore a surgical mask, no coronavirus was detected. Another study using a realistic manikin that simulated human breathing concluded that, when accounting for leakage, a surgical mask can filter at least 60 percent of 0.3 micron particles. A similar manikin study demonstrated that surgical masks reduce exposure to aerosolized influenza virus by sixfold, on average.

…but doctors and nurses have dibs on those as long as shortages last. And although the CDC hasn’t formally recommended homemade masks for the rest of us yet, remember that they have advised medical workers to use a bandana or a scarf in a worst-case scenario where medical masks aren’t available. Some protection is better than nothing. Obviously.

So why haven’t they encouraged the public to wear them yet, assuming Tucker’s wrong about them wanting to hoard masks for medical pros? One persistent argument is that mask-wearing will backfire by leading people to touch their faces more often in adjusting their masks. Nonsense, say researchers:

As for federal officials’ argument that wearing a mask will cause people to touch their face more often, Soe-Lin said she has looked for studies that back such a finding and found none. Both she and Hecht said that in their personal experience, they have been touching their faces far less often since donning face coverings. Schaffner also said he was aware of no data showing that wearing a mask could increase risk by making people touch their face more. He said he was also not aware of data showing that wearing a mask could cause a user to touch their face less often, but he said that in his own personal experience, he, too, tends to touch his face less often when he wears a mask to treat patients… “If you mandated that the entire population had to wear a mask when they went out, all those asymptomatic carriers that are now transmitting it through respiratory droplets it would be much harder for them to transmit it,” former Food and Drug Administration Commissioner Scott Gottlieb said during a video chat interview with The Wall Street Journal last week.

It may be that masks lead to less face-touching, not more. Another claim is that masks will backfire by giving people a false sense of security about infection. “If I’m wearing my mask, I can ignore the rules about social distancing,” some idiots will supposedly conclude. Also likely nonsense:

We give cars anti-lock brakes and seat belts despite the possibility that people might drive more riskily knowing the safety equipment is there. Construction workers wear hard hats even though the hats presumably could encourage less attention to safety. If any risky behavior does occur, societies have the power to make laws against it.

You could argue just as easily that masks will help reinforce the new norms about social distancing. They’re a visible reminder of the threat from COVID-19; seeing everyone around you wearing one may generate social pressure to conform and take the threat more seriously. Masks aren’t merely about protecting the wearer from being infected, after all. They’re about preventing an infected person who’s asymptomatic from unwittingly infecting others. The more of us who are wearing masks, the more the holdouts may feel inclined to join in lest they be accused of selfish recklessness.

In lieu of an exit question, here’s a tutorial on how to make your own. I imagine a couple of cotton bandanas layered over each other and then tied tightly around the head would do well enough if, like me, you don’t know how to sew.