Brief Reflections on N95 Masks

The free N95 masks are here. It’s 3M Model Aura 9205+and they’re available in many stores, including Hy-Vee and Walgreens.

I occasionally failed the fit test using this type of mask when I was working at the hospital; however, you can still get a pretty effective seal to make it protective in the community (see my video below). I was one of the few psychiatrists who had to fit test for a mask because I worked on the med-surg side of the hospital in a consult-liaison role.

The N95 flat type mask is probably no more difficult to don and doff than the surgical mask, for which the Slip Knot and Tuck method helps you achieve a pretty good seal (see my video for this).

At times, I had to use an alternative N95 mask, similar to 3M Model 1860, which is a cup-shaped mask. One year I failed the fit test for that one and I had to wear a Powered Air Purifying Respirator (PAPR). I had to wear it only once in the hospital. It was very cumbersome. Following that, I passed the fit test for the 1870+, which is similar to the 9205+.

When you search the web for more information about the N95 masks, you’ll find that there is disagreement about how to interpret eyeglass fogging pertaining to the seal. Some say that if you get any eyeglass fogging at all, you have an inadequate seal and need to fix that or “check with your supervisor.” On the other hand, others will discount that. Even the CDC says that eyeglass fogging indicates a poor seal that means that you have an inadequate seal and this should prompt the user to try another N95 model. On the other hand, others will discount that.

I did only a quick search, but found one open access article on a pilot study which concluded that “Fogging of eyeglasses is neither a sensitive nor a specific predictor for a poor fit of N95 respirators.” (Kyaw S, Johns M, Lim R, Stewart WC, Rojas N, Thambiraj SR, et al. Prediction of N95 Respirator Fit from Fogging of Eyeglasses: A Pilot Study. Indian J Crit Care Med 2021;25(9):976–980).

On balance, since no one who is not a health care professional will ever have to fit test for any N95 mask, the seal you’ll get is probably adequate. If you wear eyeglasses, remove them before donning and doffing the mask. You can get the bows caught in the straps, which can flip them off your face and into the toilet (although this has never happened to me personally). Always do hand hygiene before and after use of the mask.

I’ve read news items indicating that CDC guidelines say you should reuse the N95 only 5 times before disposing of it. It was difficult to find the source, but it’s mentioned here, under the heading “Decrease in N95 FFR fit and filtration performance” (FFR stands for Filtering Facepiece Respirator)”:

CDC recommends limiting the number of donnings for an N95 FFR to no more than five per device. It may be possible to don some models of FFRs more than five times [2]. One study reported that fit performance decreased over multiple, consecutive donnings and fit varied among the different models of FFRs examined [3]. If manufacturer guidance on how many times a particular FFR can be donned is not available, the CDC recommends limiting the number of uses to no more than five per device based on published data on changes in FFR fit from a limited number of FFR models over multiple donnings.

A recent observational study conducted in a hospital emergency room during the COVID-19 pandemic found that extended use and reuse of N95 FFRs as measured by the total hours and shifts the mask was worn and the number of donnings and doffings was associated with an increase in the fit failure of the respirators. This study also showed that it may be possible to don some models of FFRs more than five times [2]. Fit performance during limited reuse should be monitored by the respiratory protection program manager or appropriate safety personnel. 

Reference 2 is a research letter published in JAMA Network, June 4, 2020, a time when there were shortages of PPE (Degesys NF, Wang RC, Kwan E, Fahimi J, Noble JA, Raven MC. Correlation Between N95 Extended Use and Reuse and Fit Failure in an Emergency Department. JAMA. 2020;324(1):94–96. doi:10.1001/jama.2020.9843).

Further on in the CDC guidance is a section entitled “NIOSH recommends limiting the number of donnings to five for a filtering facepiece respirator. What is the science behind that recommendation?”

You can read all of this if you’re interested. I think it’s helpful to note that some experts say you can reuse them until they’re visibly dirty, which I think probably applies to users in the general community.

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