When this pandemic arrived on our shores, and much of the PPE was already hard to locate, I first went to my workshop to see what I had in the way of protective gear. I found several boxes of basic dust masks (not quite effective, but better than nothing), a couple of Plexi full-face shields (which I use on high-risk visits), and my favorite mask for dealing with chemical vapors. The last is a NIOSH (National Institute for Occupational Safety and Health) P100 respirator with dual filters attached to a rubber half-guard. And yes, a P100 is markedly better than a N95 mask.
The number in a rating tells you the minimum amount of airborne challenge particles the mask protects against: an N95 mask keeps out at least 95% of particles but isn’t oil resistant, and a P100 mask is oil proof while protecting the wearer from at least 99.8% of particles.
- PK Safety
I immediately thought “great, I’ll just use this for now”… but I was wrong. Further inspection revealed that this type of mask is fitted with an exhaust valve. Do you also see the problem here?
In an industrial setting, where these masks are usually found, the exhaust valve makes wearing one for long periods of time quite a bit more comfortable by reducing the CO2, moisture, and heat of exhalations by simply dumping them directly out of the mask through a one-way valve. See the problem now?
The hitch is that the exhaust valve does not in any way filter the air being exhausted. During industrial use, this is not an issue. The worst that would happen is that you are called out for eating that garlic & anchovies pizza for lunch.
But if you are instead looking to protect yourself, and the rest of those around you, from airborne infectious particles… this is a BIG fail. In some ways this can actually be worse than not wearing a mask at all as the exhaust valve will increase the velocity of your exhalations and, depending on the placement of the valve, this can direct possibly infectious particles right at anyone you are speaking to, and cause them to travel further than they normally would without a mask.
So I placed my lovely P100 back on the shelf and went and got myself a proper mask.
Now I see many after-market suppliers, and even some manufacturers, marketing masks that include an exhaust valve as a COVID-19 preventative measure. In fact, many of the current N95 masks being sold today are the industrial version that also include an exhaust valve (small plastic disk housing the valve). Medical professionals have known for some time about this drawback, which is why most hospitals require using only N95 masks without the valve (medical version).
Considering that I have seen little about this issue in the news, and was unable to find another diary listing this problem, I thought it might be helpful to do a quick write-up about it.
Stay safe Resisters!
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