Armbrust gets many emails praising the comfortability and breathability of our masks. Some folks even attest to the longevity of how long they can wear them before swapping out for a new mask. According to the FDA, single use means just that. Once you put it on and take it off, you toss it.
Personally, I use about a mask a day. I believe it’s a good rule of thumb. But, it helps if we break down the science of how mask defense works. In 2006, a study was conducted that the fabric in masks that actually does the work of blocking out germs and particulate matter (like COVID-19) will only last for about 24 hours once a mask is worn.
In a sense, putting a mask on your face is when the countdown begins. The fabric inside masks is charged with static electricity. This static is what’s actually blocking all the harmful stuff, including viruses, from entering the body. After a mask is used, the static wears off, rendering it less than effective. The same principle applies to older masks. If you have a box of old masks laying around in a closet for upwards of two years, you should err on the safe side and get a new box.
How often should I change my mask?
The FDA makes us say that they're single use. That means if you take it off, you throw it away you get another one. But personally, I use about a mask a day. And I think that's a good rule of thumb, generally.
For other people, though, you have to kind of figure that out for yourself but there is the question: How long will my mask remain effective?
In 2006, they did a study about this. What it said was that the the melt blown fabric that's in the mask, the special part of the mask that actually does the hard work of blocking things like COVID-19, that fabric will only last for about 24 hours of use.
Why surgical masks cannot be reused
Once you put it on your face, that starts the clock ticking. So, the way that melt blown works, it's charged with static electricity and that static electricity is actually what's blocking the virus.
And so that static electricity wears out after actual use when it’s sitting in you know the box. But that's also why you really shouldn't use old masks. If you have a box you bought two years ago gathering dust in a closet, replace it with a fresh one.