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Reprocessing Masks and Respirators

March 26, 2020

Challenging Decisions in the COIVD-19 Pandemic

The COVID-19 pandemic has left healthcare professionals faced with the difficult situation of having to reprocess N95 respirators and masks. It is important to look at prior research to inform future decisions.

The studies below consider an accurate, efficacious log reduction and flow performance.

Learning From COVID-19 in China

Can Disposable Masks be Reused After Sterilization? 

On February 9th, 2020, Fudan University Shanghai Medical College, Ministry of Education / Medical Molecular Virology Laboratory of Health Committee and School of Public Health compared five disinfection methods for reprocessing various disposable masks. 

The study was conducted in China, when medical facilities were faced with this same terribly difficult supply problem in the beginning of the COVID-19 pandemic.

UV, dry heat, and autoclave were studied as disinfection methods. Based on both antimicrobial efficacy and functionality dry heat was selected as the primary method, followed by autoclave. This would seem to make sense based on shadowing, energy loss at distance, below surface level contamination due to fluid exposure, and other issues.

The study found that dry heat at 70 C for 30 minutes is the optimal procedure for mask reprocessing. 

Learning From an Influenza Pandemic

A recently retired professional from the EPA provided two additional studies on this topic- from 2015 and 2017. These studies were done in anticipation of a PPE shortage during an influenza pandemic.

Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity (2015)

"At the higher UVGI doses, the strength of the layers of respirator material was substantially reduced (in some cases, by >90%). The changes in the strengths of the respirator materials varied considerably among the different models of respirators."

Filter quality of electret masks in filtering 14.6–594 nm aerosol particles: Effects of five decontamination methods(2017)

"Decontamination increased the pressure drop, except for N95 and Gauze masks that were decontaminated using an autoclave."