Abstract View
Decontamination and Re-Use of Surgical Masks and N95 Respirators during the COVID-19 Pandemic: Effect of Autoclave Sterilization and Ethanol Treatment on Filter Efficiency and Breathability
SERGEY A. GRINSHPUN, Michael Yermakov, Marat Khodoun, University of Cincinnati
Abstract Number: 30
Working Group: The Role of Aerosol Science in the Understanding of the Spread and Control of COVID-19 and Other Infectious Diseases
Abstract
An extraordinary demand for disposable filtering facepieces (surgical masks and N95 respirators) has substantially exceeded their supply during the COVID-19 pandemic. While disposable devices are generally not approved for routine decontamination and re-use, their decontamination and re-use widely occurred “as a crisis capacity strategy to ensure continued availability,” according the US Centers for Disease Control and Prevention, with a very limited testing conducted on how decontamination may affect the performance of a mask or respirator. We evaluated surgical masks and N95 respirators commonly used in healthcare environments with respect to their performance changes resulting from sterilization by autoclaving and treatment with 70% ethanol (alcohol). These decontamination methods are frequently utilized when filtering facepieces are being re-used in hospitals. We determined experimentally the changes in collection efficiency (filter protection factor) and pressure drop (breathability) for surgical masks and N95 filtering facepieces after applying the above disinfection treatments. The collection efficiency testing was focused on particle sizes approximately from 37 to 3,200 nm measured with an Electrical Low Pressure Impactor (ELPI) to represent the aerosolized single viruses, their agglomerates, bacteria and larger particle-carriers. It was concluded that the protection level and breathability originally offered by the tested devices may be significantly compromised by autoclaving and alcohol treatment. Quantitatively, the changes were found to depend on a respiratory protective device (type and model), particle size, breathing flow rate, type of treatment and other factors. Additionally, physical damages were observed in some models of N95 respirators after autoclaving, including a notable detachment of the nose foam, partial disintegration of the filter material around the nose clip, loss of strap elasticity and others.