N95 respiratory face masks, as well as other respiratory protection pieces, are now being reused or applied for extended use due to limited supply. The WHO as well as the CDC recommend people, especially healthcare staff and first responders use and reuse N95, KN95, and cloth masks. But, even though this sounds like a good and promising tactic to meet the demand, there is still the question of sterilization and cleaning of the masks. Is it possible to sterilize an N95 mask, and if so, what are the best methods we can utilize?
In the following paragraphs, we’re going to shed some light on the recommended reuse methods and how one should clean their N95 mask during the process of reuse. So, let’s get started!
N95 Mask And How It Works
Before we get into the cleaning and sanitizing methods, it is essential we understand what N95 masks are and how they work. N95 masks are respiratory face masks designed to have at least 95% filtering efficiency against airborne and viral particles, microorganisms, pollutants, allergens, etc. These masks have protective layers and are created to have a tight seal fit on the face, especially around the mouth and nose area. The outer layer of N95 masks is created from hydrophobic polypropylene. This ensures the filtering efficiency largely with masks like N95.
N95 masks are FDA as well as NIOSH regulated and are tested for filtration efficiency, fluid resistance, biocompatibility, and flammability. Because these masks pass all of the aforementioned tests, they can be used in an industrial environment, medical setting as well as during the COVID-19 pandemic, as approved by the WHO, CDC, FDA, and NIOSH.
N95 Mask Decontamination
Proper cleaning and sanitizing of N95 masks is difficult. There are currently no widely applicable nor studied decontamination practices that are recommended by health organizations. Some studies indicate that the use of, for example, UV light, ethanol sprays, heat exposure, or vaporized hydrogen peroxide can be effective for the decontamination of N95 masks. It is essential to mention that none of these methods have been put to any official tests and studies, so they are still not recommended practices. Nevertheless, let’s look at each of these methods and their supposed decontamination effectiveness.
N95 Masks Decontamination Using UV Light
Decontamination using UV light is already an established practice in hospitals. Even though there are no official studies and tests, non-peer research conducted by N95Decon shows that the UV-C irradiation method can be used in the decontamination of N95 FFR models with hydrophobic surfaces. The reason for this lies in the fact that UV-C light used in Ultraviolet Germicidal Irradiation of Corona Virus can effectively render the virus completely inactive in the surface mask material.
The research has been conducted in a controlled environment, with specific measurements and adequate light penetration. Regardless, the method proved promising when it comes to the decontamination of the entire mask, including the surface area as well as the headbands.
Nevertheless, N95Decon still present their study as plausible for extreme cases rather than regular decontamination method. There is still a risk of virus residue on masks even after exposure to UV-C light. Therefore, more research is required, as well as further adjustments for everyday application.
N95 Masks Decontamination Using Ethanol Spray
Another decontamination method that is being mentioned lately is the one using 70% ethanol sprays to disinfect N95 masks. Unfortunately, current research on this topic is not promising; ethanols prays are shown to impact the filtering performance of the N95 mask, especially when it comes to aerosol penetration and airflow resistance. Furthermore, ethanol spray disinfection can cause issues when it comes to user safety and irritation coming from the sprayed protective mask.
Therefore, germicidal removal from N95 masks using ethanol spray is currently not a good idea. There need to be more studies and research, especially when it comes to eradication of virus and bacteria without harming one’s health more than the actual virus and bacteria would do.
N95 Masks Decontamination Using Heat Exposure
Several studies have been performed using various heat sources regarding N95 mask decontamination. The masks were usually exposed to heat at 158°F degrees for half an hour. The purpose of these studies was to see whether the mask can be decontaminated while preserving filter integrity and efficiency. Studies that were conducted regarding the COVID-19 virus suggest that such a method could be used for several heat exposure cycles without compromising the structural and functional integrity of the mask. However, with scarce research and lack of evidence, heat exposure methods are not yet recommended by the CDC and the WHO.
It is essential to mention that the heat exposure method includes dry and moist heat sources. Unlike dry heat, moist heat has shown to be rather effective for decontamination, but it did affect the structural and functional integrity of the tested masks. Namely, the filtration efficiency of the masks lowered significantly, and the material of the mask was more susceptible to damage and deterioration.
N95 Masks Decontamination Using Vaporized Hydrogen Peroxide
Alongside the UV-C decontamination method, it seems that the vaporized hydrogen peroxide or VHP method is also gaining attention for its potential effectiveness. Research conducted by the National Institute of Allergy and Infectious Diseases shows that VHP can eliminate the SARS-CoV-2 virus from N95 masks while preserving the integrity of the mask’s fit and filtration efficiency.
According to the research, it can take the VHP up to 10 minutes to decontaminate a mask, and it can be used 3 times on the same mask and not cause damage or filtration issues. Nevertheless, the CDC has not approved this method for N95 or any mask decontamination. The reason for that lies in the lack of research and testing, which is expected to improve in the future.
N95 Cleaning Methods Not Recommended By CDC
Here’s a list of all the cleaning and decontaminating methods the CDC does NOT recommend we use to clean our N95 masks;
- Alcohol (degrades filtration)
- Bleach (degrades filtration and presents a health risk due to bleach residue)
- Ethylene oxide (toxic)
- Microwave heat exposure
- Sanitizing wipes
- Washing with soap (degrades filtration)
- Spraying with aerosol or liquid alcohol
- Overnight storage (virus remains active for 3 or more days, so overnight storage on room temperature won’t sufficiently decontaminate).
N95 Mask Storing And Reuse
So, since none of the aforementioned cleaning and sanitizing methods is approved or recommended by the global health organizations, we need to start taking care of our masks in different ways. People are generally recommended to reuse their masks for only several days, and then replace them with new ones. Proper storing and reusing methods are essential in regards to protecting the masks we wear. Here’s how you can do it;
N95 masks, just like other masks should be stored properly between uses, if one is reusing a mask. Since there are no official recommendations for mask cleaning, proper storing is the best way to keep your mask clean and protected for at least a few days. Here’s how you can properly store your mask;
- You should be the only person to wear a particular N95 mask. Do not let other people wear your mask, and don’t wear other people’s masks yourself.
- To avoid other people using or touching your mask, make sure to always store it in either a labeled paper bag or a breathable container (that has your name on it). Make sure to even label the mask yourself, by writing your name for example.
- Try storing your mask in dry places. Avoid places with humidity, as such an environment can lower the filtering efficiency of the mask. Humidity promotes quicker deterioration of the mask material. It also makes it more prone to damage and tearing, especially of the nose piece and headbands.
- Try storing your mask in a specialized N95 mask storage box. These are small, plastic boxes made to hold your masks in your bag, car while, or even pocket, keeping it clean and protected. Storing boxes can protect you and your mask from secondary pollution and cross-contamination.
According to the CDC, N95 masks can be reused for a limited number of times. The recommended reuse number is 5 times, provided the masks were properly stored between each use. However, while reusing your N95 mask for this period, it is not recommended you clean it or sanitize it. Proper storage is the only recommendation for keeping the mask clean and away from cross-contamination. However, sometimes the mask is not suitable for re-use or extended use, so here’s when you should not reuse your N95 mask;
- If the mask is visibly damaged, make sure to dispose of it and use a new mask.
- If the mask has stains or bodily fluids on it, dispose of it immediately.
- If the mask has been exposed to other people’s sneezes and coughing, make sure to get a new one.
- If you and your mask were exposed to a COVID-19 patient, make sure to dispose of the mask immediately.
- Before each new use, you need to perform a seal check to see if the mask fits properly (it needs to have a tight seal fit).
Know More: How To Store And Reuse Masks?
So, there isn’t a way you can clean your N95 mask. No cleaning methods we mentioned are approved and generally require more testing and studying. However, based on the research and information we currently have, your N95 mask should be good to use up to 5 days, without cleaning and sanitizing. After that, make sure to dispose of it properly and then use a new mask. Proper reusing and storing practices are essential in keeping your mask clean, so make sure to utilize the official recommendations and advice regarding reuse and storage.