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.

Reference

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