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Quantitative Fit Evaluation of N95 Filtering Facepiece Respirators and Coronavirus Inactivation Following Heat Treatment

Journal Article · · Annals of work exposures and health
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  1. Lawrence Livermore National Laboratory, Livermore, CA, USA
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Abstract

Reuse of filtering facepiece respirators (FFRs, commonly referred to as N95s) normally meant for single use has become common in healthcare facilities due to shortages caused by the COVID-19 pandemic. Here, we report that murine hepatitis coronavirus initially seeded on FFR filter material is inactivated (6 order of magnitude reduction as measured by median tissue culture infective dose, TCID50) after dry heating at 75°C for 30 min. We also find that the quantitative fit of FFRs after heat treatment at this temperature, under dry conditions or at 90% relative humidity, is not affected by single or 10 heating cycles. Previous studies have reported that the filtration efficiency of FFRs is not negatively impacted by these heating conditions. These results suggest that thermal inactivation of coronaviruses is a potentially rapid and widely deployable method to reuse N95 FFRs in emergency situations where reusing FFRs is a necessity and broad-spectrum sterilization is unavailable. However, we also observe that a radiative heat source (e.g. an exposed heating element) results in rapid qualitative degradation of the FFR. Finally, we discuss differences in the results reported here and other recent studies investigating heat as a means to recycle FFRs. These differences suggest that while our repeated decontamination cycles do not affect FFR fit, overall wear time and the number of donning/doffing cycles are important factors that likely degrade FFR fit and must be investigated further.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE; USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1783350
Alternate ID(s):
OSTI ID: 1785928
Report Number(s):
LLNL-JRNL--817487
Journal Information:
Annals of work exposures and health, Journal Name: Annals of work exposures and health Journal Issue: 8 Vol. 65; ISSN 2398-7308
Publisher:
Oxford University PressCopyright Statement
Country of Publication:
United Kingdom
Language:
English

References (9)

Stability and inactivation of SARS coronavirus journal April 2004
Stability of SARS-CoV-2 in different environmental conditions journal May 2020
Impact of multiple consecutive donnings on filtering facepiece respirator fit journal May 2012
Inactivation of the coronavirus that induces severe acute respiratory syndrome, SARS-CoV journal October 2004
Why does SARS-CoV-2 survive longer on plastic than on paper? journal January 2021
Can N95 Respirators Be Reused after Disinfection? How Many Times? journal May 2020
Decontamination of SARS-CoV-2 and Other RNA Viruses from N95 Level Meltblown Polypropylene Fabric Using Heat under Different Humidities journal September 2020
Modeling the Inactivation of Viruses from the Coronaviridae Family in Response to Temperature and Relative Humidity in Suspensions or on Surfaces journal July 2020
Effects of Air Temperature and Relative Humidity on Coronavirus Survival on Surfaces journal March 2010

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Related Subjects

60 APPLIED LIFE SCIENCES
N95
coronavirus
decontamination
filtering facepiece respirator
fit
heat
mask
reuse