Let's say I have used a surgical mask multiple times. And say I left it on a safe place, untouched, for three days which is the longest that viable SARS-CoV-2 has been found on different materials (Aerosol and Surface Stability of SARS-CoV-2 as Compared with SARS-CoV-1). How efficient is this mask?


Almost every public health agency is saying that disposable surgical masks shouldn't be reused but should be disposed after using them. Those who are saying surgical masks can be reused (e. g. CDC) are saying this only because there is/was a shortage of surgical masks.

But I have searched throughout the internet and couldn't find a proper explanation why surgical masks should be disposed. I did find that the middle layer of masks can be made out of microfibers with an electrostatic charge which creates the effect of electrostatic capture of microbes and that water can interfere with this charge (Wikipedia - Physical form of surgical masks). But this Wikipedia page states:

UVGI (ultraviolet light), boiling water vapour, and dry oven heating do not seem to reduce the filter efficiency, and these methods successfully decontaminate masks.

Since the water coming from our respiratory system is mostly vapour and just some droplets (this part is an assumption as I couldn't find any article confirming this statement) the argument that exhaled water discharges the electrostatic charge doesn't hold water.

So my question is - how much protection against SARS-CoV-2 does a surgical mask that has been used multiple times and that has surely been decontaminated from SARS-CoV-2 offer? Does it perhaps stay as efficient as it was at the beginning? Is it maybe just a bit less efficient than a new surgical mask? Is it as efficient as a cloth mask? A scarf? And, of course, why?


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