Face Mask Type Matters When Sterilizing, JAMA Study Finds
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When sterilizing face masks, the type of face mask and the method of sterilization have a bearing on subsequent filtration efficiency, according to a study published on June 15 in JAMA Network by the University of Oklahoma Health Sciences Center, Oklahoma City

How they tested:

5 masks of each type were sterilized with either plasma vapor hydrogen peroxide (H2O2) or chlorine dioxide (CIO2). Assessed its filtration efficacy & pressure drop. Used a mobility particle sizer to measure particle number concentration from 16.8 nm to 514 nm.

Key Insights:

• Pressure drop changes were within the acceptable range for all three mask types following sterilization with either method.

• With H2O2 sterilization yielded the least reduction in filtration efficacy in all cases. Filtration efficiencies were 96.6%, 97.1%, and 91.6% for the N95s, KN95s, and the surgical face masks, respectively.

• With ClO2 sterilization, on the other hand, filtration efficiency was maintained at above 95% for N95 masks, but for KN95 and surgical face masks, filtration efficiency was reduced to less than 80%.

• The researchers note that although overall filtration efficiency was maintained with ClO2 sterilization, there was a significant drop in efficiency with respect to particles of approximately 300 nm (0.3 microns) in size.

• For particles of that size, mean filtration efficiency decreased to 86.2% for N95s, 40.8% for KN95s, and 47.1% for surgical face masks.

Source: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2767135
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