There is research on loosely fit mask like surgical mask effectiveness compared to fit respirators, and they are much less effective. My model here is that loose fitting masks that prevent 50% - or even 95% of the particles from reaching your mouth is near-useless if someone sneezes on you, since you don’t need more than a very small number of particles to infect you. And otherwise, masks for non-sick people aren’t accomplishing much without handwashing after every time they touch the mask—especially when people still touch their mouths behind their masks, as people often do even when they know they are aerosolizing dangerous pathogens in labs. To reinforce this, anecdotally, biosafety lab workers go through training, and still need routine retraining to make sure they wear masks properly and don’t do things like eat with masks on by moving the mask out of the way.
Do you have any source for this? I remember multiple claiming that this research exists, but as I mentioned, I have so far failed to find it. The “near-useless” claim also appears to be contradicted by the study I linked in the other comment:
We estimated that, irrespective of the assumed value for the incubation period (1 or 2 days), the relative reduction in the daily risk of acquiring a respiratory infection associated with adherent mask use (P2 or surgical) was in the range of 60%–80%
Which seems like a really large amount, and was for non-fitted masks.
Thanks for that, and I have updated towards masks being more useful for non-infected people to prevent getting sick than I previously thought—though not much for the usefulness of advocating mask wearing for the public, given shortages.
I do suspect that the poorly fitting masks were useful for other reasons, like reducing hand-to-mouth contacts and increasing handwashing—which was reported as 10% higher for adherent mask wearers than non-adherent ones, potentially contributing to the effect. (It was unfortunately not reported for the control group.)
There is research on loosely fit mask like surgical mask effectiveness compared to fit respirators, and they are much less effective. My model here is that loose fitting masks that prevent 50% - or even 95% of the particles from reaching your mouth is near-useless if someone sneezes on you, since you don’t need more than a very small number of particles to infect you. And otherwise, masks for non-sick people aren’t accomplishing much without handwashing after every time they touch the mask—especially when people still touch their mouths behind their masks, as people often do even when they know they are aerosolizing dangerous pathogens in labs. To reinforce this, anecdotally, biosafety lab workers go through training, and still need routine retraining to make sure they wear masks properly and don’t do things like eat with masks on by moving the mask out of the way.
Do you have any source for this? I remember multiple claiming that this research exists, but as I mentioned, I have so far failed to find it. The “near-useless” claim also appears to be contradicted by the study I linked in the other comment:
https://www.ncbi.nlm.nih.gov/pubmed/19193267
Which said:
Which seems like a really large amount, and was for non-fitted masks.
Thanks for that, and I have updated towards masks being more useful for non-infected people to prevent getting sick than I previously thought—though not much for the usefulness of advocating mask wearing for the public, given shortages.
I do suspect that the poorly fitting masks were useful for other reasons, like reducing hand-to-mouth contacts and increasing handwashing—which was reported as 10% higher for adherent mask wearers than non-adherent ones, potentially contributing to the effect. (It was unfortunately not reported for the control group.)