Respirator and Mask Classifications
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Respirator and Mask Classifications

I've been really scrounging as of late for supplies for our hospital, getting them from any vendor I possibly could. I was pretty excited the other day to score some P100 respirators from Office Depot, which I didn't even know sold them!

(Sorry, I just checked and, while I can include the link for the ones I got in case the situation changes, right now they're out of stock.)

Before ordering I wanted to be sure I was actually helping. I wondered - What does P100 even mean? Will it protect our nurses and doctors as well as an N95? What does N95 even mean?"

I realized quickly during my shopping spree on behalf of the hospital that I knew nothing about respirators or masks. Some protect from gases, some are resistant to oil, some filter particulates - dang it's complicated! If you think about it, there are tons of industries, like construction, painting, and firefighting, that need a wide range of respiratory protection, so in retrospect it makes sense.

If you're going shopping for COVID PPE, here's what you need to know. Of note, these designations are regulated under Federal Law (42 CFR 84, in case you care), and there is a more comprehensive guide you can check out from NIOSH here; I'm going to give you the condensed version.

The letter - P, R, and N

These letters basically let you know whether or not the filter is resistant to oil. "N" respirators are not resistant to oil, while P and R do provide oil resistance.

"R" can be thought of as oil Resistant, while "P" can be thought of as oil Proof, and a big difference between R and P is their usable life. "R" respirators have a usable life of 8 hours, while "P" respirators can be used up to the manufacturer's recommendations. This is often either 40 hours of use or 30 days, but can also be "until it is hard to breathe from the filter" (which is obviously the case for all filters). No matter what you get, be sure to read the manufacturer's instructions on when the filters should be changed. I know we're in hard times, when single-use PPE even is being reused, but it's better to at least know what you're up against.

While infectious diseases don't require an oil-resistant respirator, and thus under normal circumstances healthcare facilities would rarely use them, "P" respirators provide the same level of protection against non-oil particulates as the "N" respirators, like the N95.

The number - 95, 99, and 100

The number is the minimum performance of the respirator, as a percentage of particulates over 0.3 microns that are filtered by the respirator, according to the filter test approved by NIOSH. 95% and 99% each get that number assigned, while 99.7% is assigned a 100.

Of note, there are other requirements in the test around minimum air flow, charge of the particles, etc., but that's the gist of it. Basically a higher number is a higher filter performance.

This performance level is also called filter efficiency.

As I'm sure you can tell by now, not only can P100 respirators be used when an N95 is recommended, they are actually superior to the N95 in filter efficiency (though of course this doesn't necessarily translate to a lower rate of disease transmission).


While expensive, in these desperate times a PAPR and CAPR can certainly also be used.

PAPR stands for Powered Air-Purifying Respirator. It's basically like hooking a leaf blower up to a filter and a face mask (OK it's probably more comfortable, and less noisy, than that). It sucks air through the tube, blows it through a filter, and delivers it inside a full face mask. When used appropriately with a HEPA filter, they would provide a similar level of protection as a P100 (i.e. 99.7% of particles filtered).

One advantage (in addition to being reusable) is that they don't require the user to force the air in through the filter with their lungs (hence the word "Powered"). For extended use, that can make them more comfortable.

While these are also not necessarily required for protection from COVID, they are as protective as an N95 so if you either have some on-hand or can get them they can be used.

CAPR stands for Controlled Air-Purifying Respirator and is similar to a PAPR. It can also be used in place of an N95 if needed.

This paper gives a little more of an overview on the use of an N95 versus a PAPR, if you're interested.

Some respirators are not designed for particulates

If you check out 3M's site, for example, and go shopping for respirators you'll notice some of them (or the cartridges/filters) don't have a letter or a number.

Why is that? They aren't designed for particulates. These are for completely different industries and uses and should not be purchased for protection against COVID. A good example is this one, designed for organic vapors. I'm sure it's a great filter, but COVID isn't a vapor!

The bottom line

No matter what, please save these valuable respirators for our frontline staff that need them the most. Most staff at this point can't even get a mask, much less an N95 or higher-rated respirator, which is needed when performing aerosolizing procedures.

If you're in the position like I am, and helping with getting these supplies for staff, the N95 is one of the lowest performing particulate respirators on the market; you can rest assured that any one that starts with an N, P, or R, and has a 95, 99, or 100 after it will do the job. Don't buy a respirator with none of these ratings and designed for another use.

Keywords: N95, mask, respirator, COVID-19, Coronavirus, PAPR, CAPR

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