COVID-19: Disinfection of N95 Single-Use Filtering Facepiece Respirators

Foreword

This publication uses the term “disinfection” of N95 masks to refer to the chemical or physical process that inactivates infectious agents. It should be noted that the various reference publications and documents on the subject consulted by the Centre d’expertise en retraitement des dispositifs médicaux (CERDM) use the terms “decontamination,” “disinfection,” or both. The CERDM has chosen the term “disinfection” to conform to the reprocessing nomenclature that is generally accepted in Canada (CSA Z314.18). According to this nomenclature, the term decontamination is more general and includes the process of cleaning followed by the inactivation of infectious agents. However, in the context of reprocessing of N95 masks, only one step, aimed at inhibiting various pathogenic microorganisms, is performed; therefore it seems more accurate to use the term “disinfection”.

Context

The CERDM evaluated the available options for disinfection of single-use N95 filtering facepiece respirators (masks) in the context of a shortage of filtering facepiece respirators (FFRs) in health care facilities due to the COVID-19 pandemic (INSPQ, 2020a). This represents a solution of last resort to be applied only when there is a real shortage and when all other strategies for addressing the shortage of N95 masks are insufficient, as it is not consistent with the guidelines of regulatory authorities regarding the reprocessing of single-use medical devices (SUMDs). This effort is being undertaken with the aim of identifying alternative strategies that can be added to the measures already available, to provide the best possible protection for workers in the event of a shortage.

Objective

This document is intended for decision makers, managers and clinical personnel involved in medical device reprocessing (MDR). It presents the technologies approved by Health Canada in the COVID-19 context as well as a promising - although as yet unauthorized - option for disinfecting N95 masks.

Method

The CERDM carried out a non-exhaustive review of the literature on the options for disinfecting N95 masks and contacted manufacturers of available equipment to identify the steps they have taken to validate such an approach. The CERDM also took account of any steps that have been taken within the health network that were brought to its attention. Finally, the CERDM evaluated the options identified based on the following criteria: 1) the safety of health care workers, i.e., the effectiveness of the procedure in reducing pathogen burden, the integrity of the mask after disinfection (filtration efficiency and facepiece fit) and the absence of residual chemical hazard and 2) feasibility, i.e., the availability of disinfection equipment, its performance and the requirements for the procedure (INSPQ, 2020a). These criteria are consistent with those of Health Canada (2020a).

Technologies and equipment approved by Health Canada

Low-temperature sterilizers (hydrogen peroxide plasma or vaporized hydrogen peroxide)

Disinfection of N95 masks in low-temperature sterilizers available in medical device reprocessing departments (MDRDs) is an easily accessible short-term solution that meets our evaluation criteria.

Currently, three manufacturers of low-temperature sterilizers have had their technology approved by Health Canada under the Interim Order applicable to the present pandemic (Health Canada, 2020b) and have issued disinfection instructions:

  • Stryker: Sterizone VP4
  • ASP: Sterrad 100S, Sterrad NX et Sterrad 100NX
  • Steris: V-PRO 1plus, V-PRO maX, V-PRO maX2

Consideration should be given to the fact that these models are possibly already being used for the regular activities of MDRDs. The quantity of N95 masks that can be disinfected in low-temperature sterilizers, while not negligible, is significantly lower than that which could be achieved using other devices that can perform large-scale disinfection of N95 masks.

Hydrogen peroxide vaporizer (room disinfection device)

Vaporized hydrogen peroxide is generated by vaporizing an aqueous solution of hydrogen peroxide, which is then diffused into a room by means of a room disinfection device.

The following device was approved under the Interim Order (Health Canada, 2020b):

  • Ecolab: Bioquell

This technique is an effective means of disinfecting several masks at the same time. Depending on the characteristics of the device, the size of the room and the operating parameters, this option could theoretically allow for a much higher yield than low-temperature sterilizers. This technology is rarely found at present within the health network.

Disinfection device combining several technologies (UVC, vaporized hydrogen peroxide and ozone)

The following device was approved under the Interim Order (Health Canada, 2020b):

  • Clean Works Medical: Clean Flow Health Care Mini

This device, manufactured in Ontario, is used in the agri-food industry and could disinfect up to 800 N95 masks per hour. To our knowledge, this device is not currently found in Québec health care facilities.

Technologies not yet approved by Health Canada

Promising option

Devices using UVC technology, recommended by ECRI, have applied to Health Canada to be authorized for disinfection of N95 masks.

Options not retained by the CERDM

Heat disinfection (moist or dry) was not retained as an option by the CERDM. In fact, the maximum temperature to which masks can be exposed without affecting their integrity may be insufficient to eliminate certain infectious agents, such as bacterial spores.

Tests conducted in Québec on the Nocospray device, using hydrogen peroxide nebulization, did not enable elimination of the pathogen burden and resulted in an accumulation of silver nitrate in the mask following disinfection cycles. Therefore, this technology was not retained as an option.

Recommendations

In the event of a real shortage, the CERDM recommends following:

  • The recommendations of the Comité sur les infections nosocomiales du Québec (CINQ) including that of optimizing the use of N95 masks (INSPQ, 2020 b,c);
  • The manufacturers’ instructions for the technologies approved by Health Canada for disinfection of single-use N95 masks under the Interim Order regarding the use of medical devices in relation to COVID-19 (Health Canada, 2020b), as well as the CERDM’s guidelines (INSPQ, 2020d), to develop for the facility an internal disinfection procedure, from the collection of N95 masks up to their storage.

In addition, a number of initiatives within the health network have been reported. The CERDM would like to be informed of these initiatives so it can support facilities and assist in the dissemination of information concerning the options for disinfection of N95 masks.

References

Versions

Version Date Auteur Modifications

1.0 (in French only)

2020-04-02

CERDM Creation of interim recommandations
2.0 (in French only) 2020-04-16 CERDM
  • Objective of document added
  • Technology and equipment authorized by Health Canada specified under the Interim Order with regard to COVID-19 (Health Canada, 2020b)
3.0 2020-05-21 CERDM
  • Definition of the term disinfection in the section entitled Foreword
  • Updating of technologies and equipment approved by Health Canada (addition of hydrogen peroxide vaporizer and disinfection device combining several technologies)
  • Clarification of recommendations

Notes: 

The recommendations below are based on the latest information available at the time of writing. Given that the situation and knowledge about the SARS-CoV-2 virus (COVID-19) are evolving rapidly, the recommendations in this document are subject to change.

COVID-19: Disinfection of N95 Single-Use Filtering Facepiece Respirators

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