The face masks seen in public places, required these days because of the Covid virus disease, look inadequate to me. So I have spent much of my time this week designing new ones.
The most common face masks I’ve seen appear to be little more than a piece of cloth stretched over the face by some bands pulled across the ears or behind the head. That’s totally inadequate.
I have been wearing the 3M N95 mask I purchased about five years ago when a local forest fire was creating a lot of smoke in our neighborhood. This month the local hospitals were requesting people to bring in their face masks, but this one was so old I didn’t think they would want it. I also had a “surgeon’s mask” that was being handed out at the door last summer when I was on my annual doctor’s visit. It had been worn several times too, so I didn’t turn it in.
However, I did become interested in creating a better air face mask that could be made by almost anyone, almost anywhere in the world for free, and without too much skill or time involved. Even my 3M N95 mask, which is the high standard, has several flaws in my way of thinking. One major one is that the flapper valve is a one-way air exit valve and the filtered air is mixed with the person’s exhaled air with every breath. About half the air being inhaled is, therefore, air exhaled with the previous breath. There obviously needs to be flapper valves on the incoming air as well as the exhaust air. With each breath within those 3M masks, half the air that is brought through the filter’s mask is exhaled back out through the filters.
Another problem with those form-fitting masks is that air leaks out around the edges, which becomes a problem for people wearing eyeglasses because the moisture in one’s exhaled breath condenses on the glasses. It’s a problem viewing the world through foggy glasses. Even worse, air leaks in around the edges of the mask, and that might be contaminated with Covid viruses. Also, the usual cloth masks get wet with one’s own exhaled air and stick to the face. This wet surface is probably a near-ideal place for viruses to hang out while waiting for a nose to enter.
Solving these problems and many more and designing a device isn’t a one-off design task. I have designed and tested about forty different flapper valves for making air go one way through a surface reliably and be free and easy to make from readily available materials anywhere in the world. Most of them work okay, but all of them have some limitation or another.
While writing this post I have been wearing one of my face masks and it hasn’t bothered me. I’ve usually forgotten I was wearing it, except when I wanted a sip of coffee.