Sanitation Is and Always Has Been P-Biz

Updated: Aug 7, 2020

Disclaimer: Before we talk about hygiene, #MutualAidMasks would like to ask folks to remember it's never been socially acceptable to remark about another's hygiene habits to their face. Not that it's not the substance of a lot of ostracizing "water cooler humor," but it's pretty judgemental and immature at best, to ridicule someone for a hygiene choice you probably don't understand. People make choices for reasons, instead of shaming the choice, explore the roots. The only negativity anyone needs in their lives right now is test results.#SpreadLoveNotGerms

As the virus is continually mutating and science is continuously updating its' recommendations, and there is never only one right way to do things, #MutualAidMasks believes a person's chosen decontamination processes to be very personal business. With this in mind, we share our research and findings for better personal protective measures for mask-wearing so that you may add it to your knowledge base and make more informed decisions about your own sanitation methods. If you only use these recommendations as a place from which to make your own decisions, they have done their job.

When is my mask dirty? Whoa. What a question. #MAM gets asked this all the time. While we know that mask-wearing is new and most folks have very little working knowledge of cross-contamination, were gonna just be real and let everyone know, this is kind of like being asked by someone when their underwear is dirty. So simply put, #MAM doesn't just doesn't know but we believe you do. #MAM can share some knowledge we have collected to create our own better personal protective measures to help you make your own choices.

#MAM masks are a two-layer cotton mask with a wire nose guard sewn into the seam at the top of the mask, replaceable elastic, and a third-layer of spunbond polypropylene as suggested by the WHO. We can tell you how to wash it, but not when. We even look to the CDC for guidance on that one.


#MAM recommends using CDC Recommended Guidance for Extended Use and Limited Reuse of N95 Filtering Facepiece Respirators in Healthcare Settings to establish reuse limits of both our masks and our filters as, Filti, as the manufacturer of the MERV 16 filter material does not provide this information.

CDC Recommendations for Respirator Extended Use explain that "a key consideration for safe extended use is that the respirator must maintain its fit and function….. There is no way of determining the maximum possible number of safe reuses for an N95 respirator as a generic number to be applied in all cases. Safe N95 reuse is affected by a number of variables that impact respirator function and contamination over time…[adnd] preliminary data suggests limiting the number of reuses to no more than five uses per device to ensure an adequate safety margin."

From this information, it is clear the CDC recommends that N95s should be reused no more than five times between sanitation processes and CDC recommendations for storing N95s be followed for our fabric masks and Filti filter inserts. #MAM suggests following this advice when using N95s or any other face-covering with or without a third-layer filter medium made of spunbond plastics similar to the N95 like Filti.


#MAM's fabric masks can be washed after removing the third-layer filter material. We recommend following the CDC guidelines for washing fabric masks by hand and air drying to extend the life of your masks and contain the virus:

Washing by hand

"Prepare a bleach solution by mixing:5 tablespoons (1/3rd cup) household bleach per gallon of room temperature water or 4 teaspoons household bleach per quart of room temperature water

Check the label to see if your bleach is intended for disinfection. Some bleach products, such as those designed for safe use on colored clothing, may not be suitable for disinfection. Ensure the bleach product is not past its expiration date. Never mix household bleach with ammonia or any other cleanser.

Soak the face covering in the bleach solution for 5 minutes.

Rinse thoroughly with cool or room temperature water.

Make sure to completely dry cloth face covering after washing."

Air dry

"Lay flat and allow to completely dry. If possible, place the cloth face covering in direct sunlight."

The full directions including for automatic washer and dryers can be found here.

If you choose to use a washer and dryer #MAM suggests using a delicates bag. The dryer can also wear out your elastic quicker however, #MAM mask's elastic straps are easily replaceable!

Okay so that is easy enough. Fabric masks can be washed. But filters cannot. So, how do we clean them? Well... what is your filter made of?

#MAM uses Filti non-medical grade face-mask material as its WHO-recommended third (removable) layer of filter material. Filti has filtration capabilities similar to an N95 (MERV 16). It is a non-woven spunbond polypropylene fabric similar to the materials found in industry-standard N95 masks. Since Filti is made of materials similar to industry N95s, it seems prudent to follow CDC guidelines for reuse and decontamination of N95s when approaching reuse and sanitization of Filti material.


Filti has used the CDC Crisis Standards of Care Recommendations for Decontamination and Reuse of Filtering Facepiece Respirators to establish sanitizing guidelines for Filti material. They also do an excellent job of answering questions about their material on their website. Their video suggests following the oven-based moist heat incubation method of 30 min at 160F.

#MAM reached out to the Filti because we quickly realized that most ovens do not go down to a temperature that low, which would be a barrier to sanitation for many people. Filti informed us that the material could indeed be sanitized at 170F, the most common base oven temperature, without the filtration or fabric being compromised. While this is good news, a 30-minute sanitation cycle is still a barrier in itself.

This long incubation time led #MAM to explore other sanitation methods recommended by the CDC for Crisis Standards of Care. The report states, "Based on the limited research available, as of April 2020, ultraviolet germicidal irradiation, vaporous hydrogen peroxide, and moist heat have shown the most promise as potential methods to decontaminate FFRs."

As vaporous hydrogen peroxide and ultraviolet germicidal irradiation are not readily available sanitation methods for the general public, #MAMs research focus moved to "moist heat." In Table 2 of this document, the CDC lists three potential moist heat sanitation methods with their sources. The oven-based "moist heat incubation" is considered one of the "most promising" methods and the other two "moist heat" methods are distinguished as "steam treatments" that are "promising methods with some limitation."

According to the CDC: "Steam treatment may be a suitable approach for decontaminating FFRs. The limited number of studies for steam report minimal effect on FFR filtration and fit performance and a minimum of 99.9% reduction in H1N1 influenza and bacteriophage MS2 [14, 15].

Fisher et al. used microwave steam bags, designed for disinfecting infant feeding equipment, to decontaminate six FFR models and achieved 99.9% inactivation of MS2 bacteriophage. Filtration performance of all tested FFRs scored above NIOSH certification requirements. Three FFRs were further evaluated for three cycles of steam exposure and demonstrated no change in filtration performance [15]. Bergman et al. also demonstrated acceptable filtration performance after three cycles of exposure to microwave generated steam [3]. Microwave generated steam had little effect on FFR fit after exposure to up to three cycles of steam [9, 10].

Using microwaves to produce steam to decontaminate FFRs is not without limitations. Not all microwaves are constructed the same and some are more powerful than others. The effect of higher power microwaves on FFRs is unknown. Furthermore, the metal nosebands of FFRs may cause arcing, sparks inside the microwave oven, during exposure to microwaves."

In the case of sanitizing Filti face mask material, many of the "limitations" do not apply. Namely, any limitation regarding fit because it is not a concern for a filter insert to lose shape or "fit." Metal arching in a microwave is not a limitation either, as filter inserts do not contain a metal nose bridge like an N95. So the only limitation that we need to be concerned with is the wattage of the microwave. The microwaves used in the studies went up to 1250 Watts, but were generally 1100 watts. The effect of steam on N95s generated by microwaves with higher wattages is unknown, so it is essential to use a microwave no higher than what was tested. If wattage is the only "limitation" that we have to be concerned about when using these "steam treatment" methods, which have a far less time consuming (40 seconds - 2 minutes) than the moist heat incubation method, these "steam treatment" methods should be considered viable alternatives for sanitizing Filti face-mask materials.

Microwave steam bags for baby bottles and breast pump parts are not only a quick and convenient way to sanitize Filti, but they are also cost-effective. A five-pack of Medela Microwave Sanitizer Bags is under seven dollars at most big box stores. According to the manufacturer, each bag can be used five times. So if you have a microwave, and most US households do, you can sanitize your filter(s) for about a quarter and in under two minutes.

Time and sunlight are mother nature's decontamination system, but we are still learning how to apply it to COVID-19. Time is the most straightforward sanitization method and as of April 29, 2020, science says the virus lives on plastics for seven days. Filti is a spunbond plastic. So, common sense tells us if we rotate filters in such a way that we wait seven days between uses, the filter should be been sanitized by time. As of June 29, 2020, science has shown that sunlight shortens the COVID-19 half-life, so it can't hurt to hang those filters and masks in the window or around the rearview mirror in your car.

If you combine time and sunlight with regular microwave steam treatment sanitation you can really make a high-quality filtration face mask cost-effective to use. If you have seven filters to use daily and use time to sanitize with microwave steam bags every other week just for good measure your 7 filters would last six weeks. Combining the sanitation methods makes a MERV 16 filter, with the same filtration as an industry-standard N95 available direct from the manufacturer to the general public for about a 25¢ a week.


#MAM recommends using a combination of one of the CDC Crisis Standards of Care Recommendations outlined in the "Decontamination and Reuse of Filtering Facepiece Respirators, time, and sunlight to achieve better practices of personal protective measures for sanitizing filter mediums and discarding filters after 3 sanitation cycles.

Combining the three methods not only offers some additional possible protection, but it will also extend the life of your filters and make the filtering medium more cost-effective. #MAM suggests rotating your filters between use according to how many days science is currently saying the virus can live on plastics (7 days as of this writing). If you can, doing so in a sunny window as science shows sunlight can shorten its half-life. The fewer times you use heat to sanitize the better, heat will eventually lessen the functionality of your filter and should only be used a maximum of three times as tested in the studies.

#MAM recommends deferring to the CDC whenever you are in doubt. The website is full of information backed by science and designed to be accessible by a wide range of individuals and industry professionals.

#MAM uses microwave steam bags to periodically sanitize filters in our homes. We also rotate filters between uses and place both masks and filters in the sun any chance we get. As far as how often you sanitize and which method of CDC tested sanitation you decide to use, well, that's like changing your underwear, here at #MAM we really hope you do it, but we gotta respect that ultimately when you do it is your P-Biz.

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