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 well; here are some guidelines about layers; try 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.