Coronavirus: Can homemade face masks prevent spread?

Hospitals are running low on personal protective equipment (PPE). Several have asked the public for donations, and even called for skilled individuals to sew handmade face masks. Some hospitals are specifying that these handmade masks are for patients, so they can save “official” PPE for hospital staff and medical personnel. However, I have also seen several posts featuring healthcare providers making their own masks and face shields.

How effective is homemade gear? Many doctors are sharing their opinions on this, opinions that are quite emotional, knee-jerk, angry, even. They’re saying things like “I won’t wear some stupid DIY mask made by some granny from her old undies” and “Just say NO to handmade masks– DEMAND that your hospital provide you with REAL PPE!”.

But this is a pandemic, and “official” personal protective gear is running out. So what do we do?

Well, we can’t make decisions about this without data. So what does the data show?

A widely-cited study published in 2013 in the really cool-sounding medical journal Disaster Medicine and Public Health Preparedness looked at the effectiveness of different homemade mask materials for preventing the dispersion and aerosolization of infectious particles from coughing subjects. (So, only looking at prevention of spread from an infected individual to other people.) They looked at masks made of several materials that were indeed handmade by the 21 volunteers, and compared them to standard hospital masks. Here’s what they found in graph format:

Thanks to researchers Anna Davies et al: Testing the Efficacy of Homemade Masks: Would They Protect in an Influenza Pandemic? Disaster medicine and public health preparedness.  7(4):413-418 · August 2013

Basically, vacuum cleaner bags were very effective, comparable to the actual surgical masks. But who has a bunch of those laying around? Tightly woven cotton fabric and then tea towel fabric were the most effective among fabrics. It’s worth noting that a single layer of cotton T-shirt material did prevent transmission to some degree, however.

But these researchers were concerned with Influenza virus-sized particles. Can we extrapolate to Coronavirus? Yes. Influenza particles can range from 60 to 100 nanometers in size. Coronavirus particles have been measured at about 70-90 nanometers in size, so this study is applicable. Of note, this study only looked at a single layer of fabric, and some hospitals issuing calls for handmade masks are asking for double or quadruple layers. Here is one hospital’s preferred pattern and instructions. Doubling or quadrupling the layers would provide more protection.

Remember again, though, they were looking at the ability of the masks to prevent infectious particles spewing out from the coughs of the volunteers. This was NOT a study of masks for protection of healthcare workers. So has anyone done THAT study?

Yes. A 2008 study looked at both “inward and outward” protection of various mask materials, meaning, they tested the masks’ ability to prevent particles from being breathed in, OR coughed out. The study writeup begins with the ominous statement:

With a potential influenza pandemic looming, governments need to decide how they can best use available resources to protect their people against severe illness and death, and to mitigate health and social effects for society as a whole.

Who knew? Anyways, again with Influenza virus in mind, they found that for personal protection, N-95 respirator masks were obviously the most effective, followed by hospital surgical masks, followed by handmade cloth masks. Specifically, handmade cloth masks were about half as effective as hospital surgical masks. The authors concluded:

“Any type of general mask use is likely to decrease viral exposure and infection risk on a population level, in spite of imperfect fit and imperfect adherence, personal respirators providing most protection.”

Here’s my conclusion: Obviously official PPE is best, especially for healthcare providers doing high-risk procedures like intubating patients or managing ventilators. Those folks need an N-95 respirator at least. No argument there.

But handmade masks can help several groups of people: For people who are coughing and who do not have access to a “real” surgical mask, a handmade cloth mask can help hold in some of those particles, thus protecting family members around them. Likewise, if the family members wear a handmade cloth mask, that can protect them from getting sick to some extent. I can see where these handmade masks could be really helpful out in the community, especially right now in the nods of a pandemic when “real” masks are extremely hard to come by. The handmade masks are, indeed, better than nothing.

For providers like me seeing sick and coughing patients, we don’t get N-95 masks, only surgical masks. And we’ve already been asked to conserve the surgical masks we’re issued; we now get one per shift, basically. Using a homemade mask over the surgical mask could help extend its use and efficacy. Do I have research to back that up? No, but it makes sense. Plus, the handmade cloth mask can be washed safely and re-used. Hospitals may have rules and regulations around using these during patient care, however, and one would need to check first.

Me? I won’t throw shade on handmade masks. The available data clearly shows that a handmade cloth mask is better than nothing. If we totally run out of PPE, you can bet that I’d gladly take that mask someone’s grandma made from whatever material and wear it proudly. And I bet the doctors that are objecting loudly about it right now would too.

3 thoughts on “Coronavirus: Can homemade face masks prevent spread?”

  • Drs are right to condemn homemade masks because they lead to a false sense of protection. F rom The NY Times, 3/22/2020, pg 1, ‘A Race to Deliver Much Needed Supplies…’; “Traditional SURGICAL masks can prevent sick people from spreading the virus, but they do not protect healthy people from becoming infected.” In other words, if you’re sick, wearing a SURGICAL mask is good for containing the virus. However, if you’re healthy and want protection, you need an N-95 mask. Homemade masks are about 50% as protective as surgical masks (see the how-to article above).Therefore, if you’re not sick, wearing a HOMEMADE mask will NOT protect you!! A healthy person caring for a sick person or mingling in public needs an N-95 mask for protection. If you’re sick and wear a homemade mask, do not think you are protecting those around you. Viral particles will get through.

  • Homemade masks won’t stop a viral particle, surgical masks won’t either. However, they are certainly better than no masks at all and do limit droplets getting on the face. A lot of the homemade patterns have a pocket for a couple 4x4s, some include an inner layer of T shirt fabric. Most all of them consist of at least 2 layers. Not ideal but shortage of PPE is real, especially in hard hit areas and also in small practices. With the CDC website talking about “bandanna or scarf as a last resort” when there is no PPE available it bears thinking about. After all, it wasn’t so very long ago that surgical masks were all made of fabric…and they had ties to keep them on, not elastic. They were washed and autoclaved at the hospital laundry along with the surgical drapes and gowns. I don’t think infection rates were any higher then than now. Keep in mind that N95 is a pretty recent invention. I suppose the ones who don’t want to use the ones grannies make can use bandannas…

    • Yes, it’s important to remember we aren’t that distant from cloth masks as standard. In many places (resource- poor countries) they still are the standard.

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