By Frank Long, MS, Editorial Director
What is old is new again
When those showroom-new N95s run out, clinic managers should not turn up their noses at the old N95s collecting dust.
The reason is this: Testing shows that N95s as old as 11 years past their expiration date still have better than 95% efficiency, so long as they haven’t yet been used and their elastic bands are still intact. This news comes from an article published August 11 by JAMA Internal Medicine.
Used will do
A clear lesson from the COVID-19 pandemic is that unpredictable flare-ups can swell the number of patients coming into healthcare facilities. In turn, the supplies of new N95s those facilities have depletes quickly. When those stocks run low, used N95 respirators may be an alternative.
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The JAMA study found that used N95 respirators that have undergone ethylene oxide and hydrogen peroxide turned in a fitted filtration efficacy (FFE) better than 95%. This places the efficiency of sterilized N95s in close proximity to the infection control performance of new N95s.
Even N95 respirators of the wrong size have a relatively high efficiency. According to the JAMA report, when a male study subject wore a small 1860 N95 respirator and a female study subject wore a regular size 1860 N95 respirator both still performed at greater than 90% efficiency. Masks with ear loops performed better on the male face than the female face.
What about surgical masks?
Of the 29 face masks the study tested new, expired, and sterilized N95s were the clear winners. The lagging performers were surgical and procedural masks. New surgical masks with ties were reported in this study as having 71.5% FFE.
Procedure masks with ear loops performed at 38.1% FFE. Their performance was driven even lower (21.2%) were head movements to the left and right that created gaps between the mask and the wearer’s skin.
Though the differences seem dramatic an accompanying opinion piece in JAMA questioned their significance when it comes to one particular measure.
“Although surgical masks have lower filtration efficiency than N95 respirators, observational studies have shown no significant benefit of N95 masks over surgical masks for prevention of severe acute respiratory syndrome coronavirus 1 … or other respiratory viruses … For health care workers, routine care for a patient with COVID-19 if both are wearing surgical masks is not considered to be a high-risk occupational exposure.”
Caitlin M. Dugdale, MD, Rochelle P. Walensky, MD, MPH
Effectiveness for all 29 masks tested are reported in Table 1 and Table 2 of the JAMA article, Filtration Efficiency of Hospital Face Mask Alternatives Available for Use During the COVID-19 Pandemic.
The findings of this study are important in that they may offer clinic and facility managers options for using equipment previously considered sub-par. If Dugdale and Walensky have assessed the effectiveness of surgical masks correctly, meaningful infection control options for the novel coronavirus may be even more expansive. Even the smallest edge may make a difference if COVID-19 cases surge in the fall.
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