Danish study shows face masks have no significant effect

Which the author of the article unfortunately missed completely:

> As a result, it seems that any effect masks have on preventing the spread of the disease in the community is small.

This was a solid randomized controlled study showing masks don’t protect the wearer. That’s a good start, and it’s important that everyone understands that mask are not protecting you when you go outside. People should not feel safer by putting on a mask. And if masks give people a false sense of security then that can do damage by encouraging behavior that would otherwise be avoided.

Beyond randomized controlled studies, we obviously have very strong observational worldwide evidence that even high incidence of mask wearing is not enough to prevent a seasonal outbreak. You basically need an island nation with strict border controls to do that.

To me the big remaining question around wearing a mask to protect others — since I can’t see how that’s something that can be tested in a randomized controlled study — becomes a materials science question of how these homemade masks dampen the spread of larger particles versus potentially aerosolizing smaller particles.

Was there ever any scientific study of the effect of non-surgical masks on aerosolizing the virus? I recall reading an article specifically warning against for example bandanas, or basically any single-ply cotton could actually amplify the spread.

Lastly, if some people who have mild symptoms think it’s safe enough for them to go out because they are putting a mask on, it’s likely to tilt the overall balance of help vs. harm decidedly against masks.

In short, the question isn’t really just whether surgical mask use by the general population can somewhat reduce the R factor — you’d like to think that it could, although scientifically this has not been proven and many studies show otherwise.

It’s first about homemade masks used haphazardly by the general population, and secondly it’s a behavioral question of what happens if you tell people to wear a face covering and they reasonably assume that wearing one would be somehow helpful.