Influenza and masks, redux

It's difficult to believe that it's been over a year since I last wrote a post on the use of masks in the event of an influenza pandemic. Since then, there's been a virtual glut of information out there, and from what I've seen at least, people, businesses, organizations, government, etc. interested in preparation seem to be taking more of a structured approach, rather than a knee-jerk reaction that we saw last year with Tamiflu hoarding and stockpiling masks, which, as I mentioned in the post linked above, have uncertain effectiveness in the event of a pandemic.

I also noted that one big problem is that the masks (typically recommended is the N95 mask) often don't fit properly, greatly reducing their effectiveness. Additionally, people simply don't know how to use them correctly and consistently. A new paper in Emerging Infectious Diseases confirms these statements, after observing individuals use N95 masks in post-Katrina New Orleans.

I mentioned previously the mold problem that hit New Orleans and other hurricane-ravaged areas in 2005. The soggy homes and warm conditions were perfect incubators for many species of mold, and residents were advised to use gloves and masks during their clean-up efforts. This made a good study population in which to test the use of masks during a public health disaster: fairly large numbers of people would be using them (public health officials recommended the use of N95 masks when cleaning mold), and most of those using the masks would be new to them, and hence, unfamiliar.

They found both good and bad. In the first category, the study participants did report frequently using masks for mold clean-up (86% did, typically using the N95 masks). However, many of them stated that they used them without any instruction. This is an issue with the N95 respirators, as improper fit can allow leaks to come in through the sides, significantly lowering the effectiveness of the mask. Additionally, when the investigators asked study participants to put on a mask for them, fully 80% of them were noted to have at least one error that would interfere with a proper fit:

More than half of these did not tighten the nose clip, and half incorrectly placed the 2 straps; in addition, 22% put the respirator on upside down, and 21% used only 1 strap. While 31% (n = 135) made l error, 34% (n = 146) made 2, and 35% (n = 152) made >3.

So, in a pandemic situation, the fit of the masks alone could be a big issue, and this study didn't even examine how they were actually used in the clean-up activities (e.g., did people keep them on consistently during the clean-up efforts, or did they pull them down to breathe, wipe their faces, eat in the structure, etc.?)

I think in theory, masks could be beneficial during an outbreak of respiratory disease (including an influenza pandemic), but this paper demonstrates that improper use is likely to be high, and could result in a false sense of security, thereby potentially making people less vigilant in other areas that also matter (such as hand-washing). As they note in the discussion, even some health care workers (who presumably have been trained in the use of such masks) donned them improperly while working with TB patients; it's unrealistic to expect the general population to use them better than health care workers. Therefore, I'm rather pessimistic about their ability to really protect individuals during a pandemic situation in practice, though the authors do note that "a unique opportunity exists to enhance protection of the public through interventions, such as educational campaigns, training sessions, and respirator design modifications, aimed at improving the public's ability to don a respirator correctly." Who will have the money to fund these, and who will have the time to attend them if a pandemic isn't imminent, however, is anyone's guess.


Cummings KJ et al. 2007. Respirator Donning in Post-Hurricane New Orleans. Emerging Infectious Diseases. Link.

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I don't understand why masks are not just
attached to the nose or nostrils with a tube
to your back, where the filters are.
Many advantages, but I never saw this.

Here is a link that you all can use. Its related to what you have to have to go into a work environment NOLA not withstanding. I think really they were just doing the best the could. Remember the 9th ward flooded in 1955 when the levees broke then too. People died. They didnt have PPE then and if BF comes and you dont have your own set, then you likely wont have it to work in. On the other hand the link here ensures that you can go in and ask the boss what his plans are if it comes.…

Surgical masks are just that....N95 or N100 it doesnt matter unless the air is going thru it. OSHA has covered that here

The bottom line is that if you are depending on a surgical mask to work in, it might provide some small measure of protection as its not fully sealed, it gets wet, and your eyes are not protected.

Respirators with full NBC N95 filters or N100 NIOSH filters will improve your chances dramatically and it is the standard with which the military operates...N95. Even doctors and nurses wear them in their training exercises. A suit would be very good along with booties with hard soles like the firemen wear, and elbow high certified gloves.

So do you need all of this crap? Depends. If you are going to bunker in, and dont live in your opinion where fire from a citywide firestorm or someone might come marauding in to forage for food then probably not. If it comes it will be by H2H, Cats/dogs, B2H via contact or food for both. Horses maybe, pigs from what I hear likely and it will be around for years after the initial hits. I for one cant see that we would be in masks and respirators for this kind of duration. Flu will lose its kill capability as a rule and just make you as sick after a year or two of a new strain. But this is a unique bug so anything is possible.

As for the respirator, better to have it and not need it than need it and not have it. It will be very evident around you and your home if you need one. Its also an escape mask if a fire breaks out as the -95's and -100's wont filter that out. I will say though having been in them for days on end with only short breaks out in a decontamination area, you had better make sure it does fit properly and check it at all times.

If you just have a mask you are going to have to decon just to go home each day so it presents very unique problems as you will have virus on your body, your mask, your clothing. Lots to consider here, all bad.

By M. Randolph Kruger (not verified) on 14 Apr 2007 #permalink

gsgs, you say

I don't understand why masks are not just
attached to the nose or nostrils with a tube
to your back, where the filters are.
Many advantages, but I never saw this.

You would need an airtight seal for the mouth as well as the nostrils - which would be unbearably discomforting. And to breathe through tubing is unpleasant and difficult - it also increases the "dead space" of the airways, leading to carbon dioxide retention.