Some decontamination processes damage N95 face masks
Scientist tests hospital masks processed up to 10 times for reuse

Date:
July 16, 2020
Source:
University of Massachusetts Amherst
Summary:
Certain methods of decontaminating medical face masks for repeated
use during the COVID-19 pandemic appear to damage the masks'
integrity and protective function, according to new research.



FULL STORY ========================================================================== Certain methods of decontaminating medical face masks for repeated use
during the COVID-19 pandemic appear to damage the masks' integrity
and protective function, according to research by a University of
Massachusetts Amherst environmental health scientist.


========================================================================== "Some treatments for decontamination had no impact on respirator
performance, while other treatments resulted in substantial damage to
masks," writes Richard Peltier, associate professor in the School of
Public Health and Health Sciences and lead author of the paper published
July 16 in the journal Infection Control and Hospital Epidemiology.

Peltier received a fast-track grant from the National Science Foundation
in May to study the impact of various sterilization techniques authorized
for emergency use by the Food and Drug Administration (FDA) in light of
the shortage of medical face masks, also known as N95 respirators.

"Given the global N95 shortages, clinicians face a choice: wearing a
used, and potentially infected respirator, or wearing one that was decontaminated through a process that may affect the integrity of
the respirator," says Peltier, whose co-authors include doctors and
researchers at New England Baptist Hospital in Boston and UMass Memorial Medical Center in Worcester.

Peltier uses state-of-the-art pollution detection instruments and a
mannequin head in his lab to measure whether microscopic particles can
pass through the masks after they are sterilized. "Respirators must be effective across a range of potential conditions to provide protection
since droplets that contain virus particles immediately start to evaporate
and shrink," he explains.

While the testing was limited by the availability of processed masks
provided by hospitals in Massachusetts, the study draws several
generalizable conclusions, Peltier says.

Respirators that were treated between one and 10 times with specific
vaporized hydrogen peroxide (vHP) sterilizers or up to five times
with shorter decontamination cycles of gas plasma hydrogen peroxide
(gpHP) retain their original filtration capabilities. A decontamination
process using ultraviolent germicidal irradiance (UVGI) slowly diminishes filtration efficiency, reaching a level "that warrants caution" after
nine repeated treatments, the research found. "However, there are still
a number of sterilizer systems that are being used on these masks which
we don't have information about and therefore can't determine if they
keep workers safe," Peltier says.

Treatments with high concentrations of gpHP or longer processing times
degraded filtration performance below the requirement for N95 masks,
which should be capable of filtering 95% of 300 nanometer (nm) particles.

For comparison, Peltier also tested a KN95 mask, some brands of which have
been removed from the FDA's emergency-use list due to poor performance,
and a four- ply polyester bandana. Neither had been treated with any decontamination technique, and both performed below N95 standards. Peltier
also found that immersing an N95 mask in a 10% bleach solution degraded
its performance.

Peltier notes that his study did not address the masks' fit or
general integrity, including elastic function, corrosion on staples
and compression of the respirator, all of which are important for
proper functioning. His research highlights the importance of using decontamination techniques shown to be safe for the reuse of N95 masks.

"We hope this work supports good decision-making that protects those who
are on the front lines of this pandemic keeping us all safe," Peltier
says. "Without them, none of us are safe."

========================================================================== Story Source: Materials provided by
University_of_Massachusetts_Amherst. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Richard E Peltier, Jiayuan Wang, Brian L. Hollenbeck, Jennifer
Lanza,
Ryan M. Furtado, Jay Cyr, Richard Ellison, Kimiyoshi J. Kobayashi.

Addressing Decontaminated Respirators: Some Methods Appear to
Damage Mask Integrity and Protective Function. Infection Control &
Hospital Epidemiology, 2020; 1 DOI: 10.1017/ice.2020.332 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200716220918.htm

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