Research on Cloth Face Masks – ARE THEY EFFECTIVE??
The big questions… are cloth face masks effective?
In our current Covid-19 epidemic, there are many questions about what we should be doing to protect ourselves and others. Unfortunately, there is also a shortage of PPE (personal protective equipment) for healthcare providers.
Many groups on Facebook and in communities have turned to sewing cloth face masks and donating them to help the efforts of those caring for the sick. This is such a wonderful group effort, but will these efforts just go to waste?
This was the question I asked and as a nurse, I turned to the research. There is some research out there on cloth face masks, but mostly it’s quite limited. This may be why organizations like the CDC and WHO are hesitant to clearly state their opinions on cloth face masks.
So… what did my research say? You can watch it in this video if you prefer, but I’ll list my findings below along with all my cited works at the end.
Are they Effective???? THE BIG QUESTION
First, there are 2 types of masks commonly used by medical professionals. Medical masks and respirators.
“The major differences between medical masks and respirators are their intended uses and levels of protection. A medical mask is intended to protect others from large droplets exhaled or released by the wearer. It is also designed to protect the wearer’s respiratory tract from splashes of body fluids that may unexpectedly occur in the clinical setting. In contrast, a respirator is designed to protect the wearer from hazardous contaminants in the air.”1
Here we are talking about medical masks. Some masks include a place for a filter to increase the effectiveness of protection, and some cloth mask makers even include a “pocket” in their design so HCPs can place a filter in if they have one. I think that’s a great idea.
Study from Oxford
Oxford tested penetration levels for cloth masks at 2 different speeds. The study didn’t specifically say what the cloth masks were made of, but along with “cloth masks” there were multiple fabrics tested including t-shirts, towels, sweatshirts, and scarves.
So when they looked at bacteria sized particles, the penetration levels of cloth masks was about 75-90%, which seems quite high, but definitely better than nothing. This means that you’re only protected from about 10-25% of (large) particles coming your way.
A N95 respirator was much much better at a 1-3% penetration rate, but that is to be expected.
When they tested smaller particles (like the size of a virus), the rates are even worse, which is also to be expected. You can see, compared to a respirator, there is a significant difference. ALOT more virus sized particles are penetrating through.
“The use of fabric materials may provide only minimal levels of respiratory protection to a wearer against virus-size submicron aerosol particles (e.g. droplet nuclei). A poor filtration performance is expected for improvised fabric materials because these materials are not designed for respiratory protection.”2
So here’s what they concluded:
“In spite of the poor performance, fabric materials may provide some level of protection against the transmission of infectious aerosols when used in combination with other protective measures.”2
Are they better than nothing?
There are basically two schools of thought here. You can read through these 2 differing opinions and see which one resonates the most with you.
Here’s a potential “pro” of using a mask, even if it’s a cloth face mask.
“Moreover, cloth masks and fabric materials covering the mouth and nose may serve as a reminder to not touch those areas with the hands serving to minimize contact transmission and reduce exposure to liquid splashes and droplets.”2
And then here’s a potential “con” of using a cloth face mask.
“There is currently a concern that cloth mask use may give users a false sense of protection in the absence of proven efficacy that will encourage risk taking and/or decrease attention to other hygiene measures.”3
If you’re already wearing a cloth mask most places, which of these 2 categories do you fall into? If you haven’t ventured there yet, consider the facts of efficiency and be careful not to engage in behaviors you wouldn’t do without a mask (i.e. standing closer to people, touching your face to readjust, etc).
What does the CDC say?
I had to dig PRETTY far down to find the LAST paragraph of an article from the CDC to find anything about the use of cloth masks. Again, the research available is just not enough to make good conclusions about cloth face masks. Here’s what they said:
“In settings where facemasks are not available, HCP might use homemade masks (e.g., bandana, scarf) for care of patients with COVID-19 as a last resort. However, homemade masks are not considered PPE, since their capability to protect HCP is unknown. Caution should be exercised when considering this option. Homemade masks should ideally be used in combination with a face shield that covers the entire front (that extends to the chin or below) and sides of the face.”https://www.cdc.gov/coronavirus/2019-ncov/hcp/ppe-strategy/face-masks.html#crisis-capacity
Other countries are doing it??
If you’re reading this from the US, you may have quite different thoughts about the topic than those from other countries, especially in Asia where masks (even cloth) are frequently used.
“Although cloth masks are commonly used in low/ middle income countries, there is minimal policy acknowledgment of the need for cloth masks, and a lack of evidence on their efficacy and use. Cloth masks are generally not mentioned in any policies on the use of PPE during an influenza pandemic. The lack of recommendations for respiratory protection may be due to a lack of evidence on their efficacy. Despite the lack of evidence and the little attention paid to cloth masks in guidelines and policies, they continue to be widely used around the world, particularly in resource-poor countries.”4
“All types of masks reduced aerosol exposure, relatively stable over time, unaffected by duration of wear or type of activity, but with a high degree of individual variation. Personal respirators were more efficient than surgical masks, which were more efficient than home-made masks.
Personal respirators are the most effective, then surgical masks, then home-made masks. Unfortunately, we are headed to such a shortage where the least effective option may be the only option!
Outward protection (mask wearing by a mechanical head) was less effective than inward protection (mask wearing by healthy volunteers).”5
How much will wearing a cloth mask decrease your exposure to infection? We still just don’t have enough data for that. Perhaps, after this Covid-19 epidemic more emphasis will be placed on studying cloth masks, which kinds are most effective, and other options for protection when another crisis like this occurs.
Here is a final thought.
“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.”5
So, what do you think? Is it worth it? Will you be making some? Comment on the YouTube video and tell others what you think!
1: 2 Characteristics of Respirators and Medical Masks.” Institute of Medicine. 2006. Reusability of Facemasks During an Influenza Pandemic: Facing the Flu. Washington, DC: The National Academies Press. doi: 10.17226/11637. Page 39
2: Samy Rengasamy, Benjamin Eimer, Ronald E. Shaffer, Simple Respiratory Protection—Evaluation of the Filtration Performance of Cloth Masks and Common Fabric Materials Against 20–1000 nm Size Particles, The Annals of Occupational Hygiene, Volume 54, Issue 7, October 2010, Pages 789–798, https://doi.org/10.1093/annhyg/meq044
3: Chughtia, A. A., Seale, H., & MacIntyre, C. R. (2013). Use of cloth masks in the practice of infection control – evidence and policy gaps. International Journal of Infection Control. doi: 10.3396/IJIC.v9i3.020.13 https://pdfs.semanticscholar.org/f0b3/1640fd555dfc32d44af2009bacc416273ef9.pdf
5: van der Sande, M., Teunis, P., & Sabel, R. (2008). Professional and home-made face masks reduce exposure to respiratory infections among the general population. PloS one, 3(7), e2618. https://doi.org/10.1371/journal.pone.0002618