How Much Mask-Wearing Do We Need?

Just how much mask-wearing do we need? That depends on how good our masks are. If they’re highly efficient, we can get by with fewer people wearing masks. If they’re not so great, we need a lot more people wearing them. Alan Kot has deployed a vast flotilla of Greek letters to come up with a theoretical model that produces this chart:

Each of these curves represents a disease with a particular value of R0 and shows what it would take to get R0 down to 1.0. COVID-19, for example, has an R0 of about 2.5, so take a look at that curve. On the bottom right, it shows that you can get this down to 1.0 with 100 percent of the population wearing masks that are about 35 percent efficient. At the top of the curve, you can achieve the same result with 60 percent of the population wearing masks that are 100 percent efficient. Anyplace else along the curve also works.

Fine. So how efficient are the cloth masks that we’re all wearing these days? I’m glad you asked:

The obvious problem with some of these is that, efficient or not, you’d barely be able to breathe through them. But how about silk or chiffon? They look to be about 50-60 percent efficient and are probably breathable. If we could get 80 percent adoption of masks like this, Kot says, that would be enough to get R0 below one and extinguish the the pandemic entirely.

Wear a mask! With the exception of 80 thread-per-inch quilter’s cotton, they’re all effective enough to make a difference.

UPDATE: I originally misinterpreted Kot’s chart. It’s corrected now.

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THE BIG PICTURE

You expect the big picture, and it's our job at Mother Jones to give it to you. And right now, so many of the troubles we face are the making not of a virus, but of the quest for profit, political or economic (and not just from the man in the White House who could have offered leadership and comfort but instead gave us bleach).

In "News Is Just Like Waste Management," we unpack what the coronavirus crisis has meant for journalism, including Mother Jones’, and how we can rise to the challenge. If you're able to, this is a critical moment to support our nonprofit journalism with a donation: We've scoured our budget and made the cuts we can without impairing our mission, and we hope to raise $400,000 from our community of online readers to help keep our big reporting projects going because this extraordinary pandemic-plus-election year is no time to pull back.

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