Glimpse: Assume Twice About Reusing KN95 or Surgical Masks

For sterilizing N95, KN95 and surgical masks, plasma vapor hydrogen peroxide became as soon as superior to chlorine dioxide in conserving the products’ filtration efficiency in a lab gaze.

Masks sterilized as soon as with chlorine dioxide showed a marked reduction in total filtration efficiency especially amongst KN95s and surgical masks, reported Changjie Cai, PhD, and Evan Floyd, PhD, both of the College of Oklahoma in Oklahoma City, in a JAMA Community Launch compare letter.

Point out filtration efficiencies sooner than sterilization had been 97.3% for N95 masks, 96.7% for KN95 masks (a Chinese model of N95s), and 95.1% for surgical face masks.

When publish-sterilization filtration efficiency became as soon as stratified by aerosol particle size, the imply for KN95s and surgical masks dropped to below 50% for particles of roughly 300 nm when sterilized with chlorine dioxide. N95 mask efficiency decreased to roughly 86% with chlorine dioxide for particles of 300 nm, even when total filtration efficiency became as soon as roughly 95%.

Exiguous degradation became as soon as seen with plasma vapor hydrogen peroxide at all aerosol sizes, the researchers chanced on.

“To greater protect successfully being care personnel in hospitals, we recommend measuring the respirator’s filtration efficiency by aerosol size as an different of finest measuring the total filtration efficiency,” Cai and Floyd wrote.

They much that, on account of potential inner most protective equipment (PPE) shortages valid via COVID-19, varied sterilization techniques have been evaluated in makes an try to reuse N95 masks. Then another time, no compare tested the feasibility of reusing KN95 masks or surgical masks.

After sterilization with plasma vapor hydrogen peroxide, both N95s and KN95 masks had no no longer up to 95% efficiency, even when efficiency of the surgical mask became as soon as described as “diminished.” Then another time, after chlorine dioxide sterilization, total filtration efficiency dropped to 76.2% for KN95 masks and 77.9% for surgical masks, even when it became as soon as accumulated 95.1% for N95 masks.

Examining sterilization by filtration efficiency by aerosol size for particles of roughly 300 nm, the authors told “warning needs to be exercised” when the use of KN95s and surgical masks, whose imply filtration of 300 nm particles dropped to 40.8% and 47.1%, respectively, following chlorine dioxide remedy.

“As successfully as to contemplating the total filtration efficiency, the filtration efficiency for particles much like infectious brokers needs to be opinion of,” the authors cautioned.

A predominant limitation of the gaze became as soon as that results of repeat sterilization cycles weren’t examined; Cai and Floyd careworn out that “filter area topic can even degrade further after just a few cycles, which might perhaps perchance even accumulated even be investigated.”