See also: This.
These days surgical masks are in high demand and short supply, especially for the general public. So homemade cloth masks have been recommended by the CDC and other health agencies.
Some conservatives won’t be satisfied until they are shown conclusive proof that homemade cloth masks are effective. Indeed, scientists disagree on the precise effectiveness of them.
But Covid-19 is a brand new disease, and the absence of evidence at this point is not evidence of absence. it stands to reason cloth masks provide *some* protection, both to yourself and others, as they do filter the air. And they are ridiculously easy to wear.
So don’t overthink it. Just wear them.
That said: Stay away from crochet masks that have wide holes that stretch even further when applied to the face. Those obviously won’t do the job.