With the spread of COVID-19, high-quality medical masks are in short supply. As a result, many regular citizens and healthcare workers have been forced to reuse single-use medical masks. While this is not the ideal option, many people have had no choice but to sterilize and reuse masks to remain safe. Since sterilization is extremely important for the process of reusing masks safely, we will go over the best methods to sterilize your medical masks and stay safe during the pandemic.

What Does the CDC Say About Medical Mask Sterilization?


The Centers for Disease Control and Prevention (CDC) provide a wide array of information related to safety protocols for healthcare workers and regular citizens. According to the CDC, all other options should be exhausted before you consider sterilizing or reusing a medical mask. Mask reuse greatly increases the chances of self-contamination or the contamination of others. However, the CDC also provides guidelines related to the sterilization of medical masks. More specifically, the agency lays out important information regarding the decontamination of Filtering Facepiece Respirators (FFRs). Here’s what the CDC recommends:


“Decontamination is a process to reduce the number of pathogens on used FFRs before reusing them. It is used to limit the risk of self-contamination. Decontamination and subsequent reuse of FFRs should only be practiced where FFR shortages exist. Decontamination should only be performed on NIOSH-approved FFRs without exhalation valves.


At present, FFRs are considered one-time use products, and there are currently no manufacturer-authorized methods for FFR decontamination before reuse. Only respirator manufacturers can reliably provide guidance on how to decontaminate their specific models of FFRs. In the absence of manufacturer’s recommendations, third parties, such as decontamination companies, safety organizations, or research laboratories, may also provide guidance or procedures on how to decontaminate respirators without impacting their performance.


An effective FFR decontamination method should reduce the pathogen burden, not harm the fit or filtration performance of the FFR, and should present no residual chemical hazard. NIOSH reviewed the literature on decontaminating FFRs because of these considerations. NIOSH found that, as of April 2020, ultraviolet germicidal irradiation, vaporous hydrogen peroxide, and moist heat have shown the most promise as potential methods to decontaminate FFRs.

On March 29, 2020, the U.S. Food and Drug Administration (FDA) issued the first Emergency Use Authorization (EUA) for a process to decontaminate, and subsequent EUAs have been issued. Healthcare facilities should check the FDA Emergency Use Authorizations website

external icon for the most up-to-date information.


The effectiveness of using any of the methods mentioned in this guidance should be explored with specific FFR models and with the manufacturer and, if needed, third party expert input and support to better understand the impact on respirator performance, including filtration and fit, and structural integrity, including integrity of head straps and other parts.


Employers should be able to demonstrate effectiveness of any decontamination methods used against the likely contaminants (i.e., pathogens) of concern including SARS-CoV-2. Employers should also ensure that any decontamination methods used, including those for which an FDA EUA has been issued, do not produce additional safety hazards (e.g., electrical arcs resulting from placing FFRs with metal parts into microwaves), or that workers are adequately protected from those hazards through appropriate engineering and administrative controls, safe work practices, and personal protective equipment.


Decontamination might cause poorer fit, reduced filtration efficiency, and reduced breathability of disposable FFRs as a result of changes to the filtering material, straps, nose bridge material, or strap attachments of the FFR. Decontamination may produce chemical inhalation risks and should be evaluated for off-gassing.


While decontamination and subsequent reuse of FFRs void the NIOSH approval and are not permitted under OSHA’s respiratory protection standard during normal conditions of use, these options may need to be considered during a crisis capacity situation when FFR shortages exist.”


To summarize the information above, medical masks should only be decontaminated when it is absolutely necessary (i.e. medical mask shortages). If you have access to more PPE that meets NIOSH standards, you should not attempt to sterilize your medical mask. As it currently stands, there is no “one-size-fits-all” sterilization method for medical masks. The exact procedure you follow will depend on the type of medical mask you’re using and the guidelines and recommendations of its manufacturer. 


That said, the CDC recommends that any mask sterilization focuses on achieving the following results


  • Reducing pathogen burden
  • NOT reducing fit or filtration performance
  • Avoiding residual chemical hazard


As of the latest data, the CDC recommends three potential methods for sterilizing or decontaminating medical masks:


  • Ultraviolet germicidal irradiation
  • Vaporous hydrogen peroxide 
  • Moist heat 

However, it is extremely important to remember that any of these methods could jeopardize the efficacy of your medical mask. These methods could reduce filtration, breathability, or even fluid splatter protection. Nonetheless, as mentioned above, the FDA unofficially “approved” certain methods for sterilizing medical masks if and when it becomes necessary.

What are the FDA Methods for Sterilizing Medical Masks?


As the primary regulatory agency of medical equipment in the United States, the FDA provides the final word on all things related to medical mask safety. Naturally, this includes the potential sterilization and reuse of single-use medical masks. In the past, the FDA advised against reusing medical masks. However, the unprecedented strain on medical supplies caused by COVID-19 has pushed the FDA to revise its mandates regarding mask reuse and contamination. 


As of August 2020, the FDA provides the following methods for sterilizing and reusing medical masks:


Sponsor

Authorization Date

Product

Description

Battelle

3/29/2020

Batelle Decontamination System

A single compatible respirator to be recycled and reused up to 20 times using the Battelle Decontamination System.

STERIS

4/09/2020

STERIS V-PRO 1 Plus, maX, and maX2 Lower Temperature Systems

Decontaminates compatible N95 or N95 equivalent respirators (compatible N95 respirators) for single-user reuse by healthcare personnel.

Advanced Sterilization Products (ASP)

4/11/2020

STERRAD Sterilization System

Decontaminates compatible N95 or N95-equivalent respirators for single user reuse by healthcare personnel to prevent exposure to airborne particulates when there are insufficient supplies of N95 respirators.

Stryker

4/15/2020

STERRIZONE VP4 N95 Respirator Decontamination Cycle

Decontaminates compatible N95 or N95 equivalent respirators (compatible N95 respirators) for single-user reuse by healthcare personnel.

Sterilucent, Inc. 

4/20/2020

Sterilucent, Inc. Sterilization System

Decontaminates compatible N95 or N95 equivalent respirators (compatible N95 respirators) for single-user reuse by healthcare personnel.

Duke University Health System

5/7/2020

Duke Decontamination System

Decontaminates compatible N95 or N95 equivalent respirators.

STERIS

5/21/2020

STERIS STEAM Decon Cycle

Decontaminates compatible N95 respirators for single-user reuse by HCP to prevent exposure to pathogenic biological airborne particulates when there are insufficient supplies of face-filtering respirators (FFRs) resulting from COVID-19.

Stryker

5/27/2020

Stryker VHP Decontamination System

Decontaminates compatible N95 respirators for multiple-user reuse by healthcare personnel to prevent exposure to pathogenic biological airborne particulates when there are insufficient supplies of face-filtering respirators resulting from the COVID-19 pandemic.

Technical Safety Services LLC

6/13/2020

Technical Safety Services VHP Decontamination System

Decontaminates compatible N95 respirators for multiple-user reuse by healthcare personnel (HCP) to prevent exposure to pathogenic biological airborne particulates when there are insufficient supplies of face filtering respirators resulting from COVID-19.

Michigan State University

7/24/2020

Michigan State University Decontamination System

Decontaminates compatible N95 respirators for single user reuse by healthcare personnel to prevent exposure to pathogenic biological airborne particulates when there are insufficient supplies of face-filtering respirators (FFRs) resulting from COVID-19.

NovaSterilis, Inc.

08/20/2020

Nova2200

Decontaminates compatible N95 respirators for single-user reuse by healthcare personnel (HCP) to prevent exposure to pathogenic biological airborne particulates when there are insufficient supplies of face-filtering respirators (FFRs) resulting from the COVID-19.


You can learn more about each of these sterilization and decontamination methods from the FDA website.

How to Safely and Effectively Sterilize Your Medical Masks


Now that we’ve covered what the experts have to say about mask sterilization, it’s time to look at actual steps you can take to sterilize your own medical masks. While non-medical masks can be easily sterilized with traditional washing methods, medical masks are more complex. As a result, sterilizing medical masks is not something you can do with household cleaning products. However, there are several processes you can follow to sterilize medical masks — as long as you have the right equipment.

Ultraviolet Germicidal Irradiation


Fortunately, you can pick up any number of ultraviolet germicidal devices through online retailers. Using ultraviolet light, these devices can kill up to 99.9% of bacteria or viruses in the air or on surfaces. While there have been no conclusive studies on the efficacy of this solution in relation to medical masks, ultraviolet germicidal irradiation has been approved as an emergency solution to clean and sterilize contaminated safety masks. If you’d like to learn more about acquiring an ultraviolet device, consult American Ultraviolet.

Vaporous Hydrogen Peroxide 


Vaporous Hydrogen Peroxide (VHP) is a low-temperature vapor that can effectively sterilize medical equipment, including medical masks. However, this method is much more complex and expensive than ultraviolet solutions. You will need to acquire highly technical equipment from manufacturers like STERIS. That said, it is also believed to be the most effective and efficient option, making it the most common solution among medical professionals.


According to the CDC, VHP involves the following process and benefits:


“One method for delivering VHP to the reaction site uses a deep vacuum to pull liquid hydrogen peroxide (30-35% concentration) from a disposable cartridge through a heated vaporizer and then, following vaporization, into the sterilization chamber. A second approach to VHP delivery is the flow-through approach in which the VHP is carried into the sterilization chamber by a carrier gas such as air using either a slight negative pressure (vacuum) or slight positive pressure. Applications of this technology include vacuum systems for industrial sterilization of medical devices and atmospheric systems for decontaminating for large and small areas853. VHP offers several appealing features that include rapid cycle time (e.g., 30-45 minutes); low temperature; environmentally safe by-products (H2O, oxygen [O2]); good material compatibility; and ease of operation, installation and monitoring.” 


For more information on VHP, consult the STERIS VHP Sterilization & Biodecontamination page.

Moist Heat


Finally, you can sterilize medical masks without degrading their quality by using moist heat steam sterilizers. This method has been used for years to sterilize surfaces in hospitals and medical clinics. However, it is now being used to sterilize medical masks. Unfortunately for consumers, it can be difficult to acquire the right equipment and replicate the necessary environment to make this method an effective at-home sterilization method. That said, it’s not impossible.


According to the CDC, you can do the following to sterilize medical equipment with moist heat:


“The basic principle of steam sterilization, as accomplished in an autoclave, is to expose each item to direct steam contact at the required temperature and pressure for the specified time. Thus, there are four parameters of steam sterilization: steam, pressure, temperature, and time. The ideal steam for sterilization is dry saturated steam and entrained water (dryness fraction ≥97%).813, 819 Pressure serves as a means to obtain the high temperatures necessary to quickly kill microorganisms. Specific temperatures must be obtained to ensure the microbicidal activity. The two common steam-sterilizing temperatures are 121°C (250°F) and 132°C (270°F). These temperatures (and other high temperatures)830 must be maintained for a minimal time to kill microorganisms. Recognized minimum exposure periods for sterilization of wrapped healthcare supplies are 30 minutes at 121°C (250°F) in a gravity displacement sterilizer or 4 minutes at 132°C (270°F) in a prevacuum sterilizer (Table 7). At constant temperatures, sterilization times vary depending on the type of item (e.g., metal versus rubber, plastic, items with lumens), whether the item is wrapped or unwrapped, and the sterilizer type.”


You can learn more about moist heat sterilization from the CDC website.

Conclusion


As you can see, figuring how to sterilize your medical masks can be complicated. If you work in the healthcare industry and have access to certain equipment, you’ll likely have more options. However, for the average consumer, ultraviolet germicidal irradiation is the best option. This solution can also be combined with standard chemical disinfectants to reduce the risk of remaining pathogens. However, you must be careful not to use chemicals that will be toxic for you or products that will compromise the efficacy of your medical masks.