What Common Household Item Might Improve the Effectiveness of Homemade Face Masks By Up to 50%?

I thought my pantyhose-wearing days were over, but guess what…THEY’RE BACK! Except now I’m not wearing them around my pelvis, but around my face, because researchers from Northeastern University found that adding pantyhose over homemade cloth masks can boost the performance of the masks by up to 50%!

Two researchers–Dr. Amy Mueller and Dr. Loretta Fernandez, both Assistant Professors at Northeastern University in the departments of Civil & Environmental Engineering and Marine & Environmental Sciences–collected homemade masks from volunteers in Boston who were donating them to area hospitals. The scientists used an instrument called a PortaCount to measure the ability of the masks to filter particles ranging from 20 nanometers to 1,000 nanometers (the coronavirus is approximately 60 to 140 nanometers in diameter). The tight-fitting N95 respirator used in hospitals can blocks at least 95% of small particles; a 3-M surgical mask blocks about 75%.

In the research project, homemade cloth masks vary widely, with some blocking less than 30% of the particles. HOWEVER, when a band of nylon from pantyhose was worn on top of the face mask, the mask’s performance jumped by 15-50%. The repurposed pantyhose make the mask fit much more closely to the face, reducing the amount of particles that are escaping past the edges of the mask and forcing them through the mask instead.

In some of the tests, a high-quality homemade face mask–that is, a mask with multiple layers of thick-weave cotton with some filter material inside–performed up to around the same levels as the surgical mask. With that level of performance and face fitting, it is believed that the masks not only reduce the spread of germs from the wearer to others, but may better protect the mask wearer from breathing in particles from other people.

The study also showed it was effective in improving the protection of the paper masks as well. They discovered that putting the nylon overlay over the surgical mask boosted its filtration ability almost up to the N95 respirator performance levels

The great thing is that it is an easy fix. I know, because I tried it myself before writing this post. All you need to do is to cut off one leg from the pantyhose “panty” part (Queen size is suggested), then cut off a band about 8 inches long from the top of the leg. You pull that band over the top of your head and under your hair (if it is long like mine is) like you would put on a headband, letting it rest at the bottom of your neck. Next you put on your face mask. Then you pull the nylon band over your face mask, allowing the bottom of the band to wrap under and around your chin and the top to slide slightly above the top of your mask.

It really does work! It covers your entire mask but pulls all the edges snug to your face, reducing the ability of air to pass around the edges of your mask instead of through your mask. I didn’t wear it for very long, but it wasn’t hot or uncomfortable or add to any difficulties in breathing (I have asthma, so too-thick masks can be a problem for me). I don’t have any way to measure filtration levels, but I could definitely see the mask fit much more snuggly, so it makes sense to me that would be more effective.

In addition, at least in my case, since I don’t have a sewing machine, my homemade face masks are not that great and have a tendency to slip or fall apart completely, so I feel much more secure with the pantyhose helping to keep them in place. If the mask is more secure, I am less likely to have to touch it to adjust or fix it while I’m wearing it, which reduces the probability of contaminating the mask with my hands.

Therefore, I am willing to “sacrifice” my former pantyhose to help keep myself and my neighbors safe and healthy.

Now, this is only one study, and it is new and hasn’t been peer-reviewed, etc. So I don’t want to overhype it or present it as a magical cure or even suggest it should replace other safety practices such maintaining social distancing and washing hands often and thoroughly. I feel like it makes my mask work better, so now anytime I wear a mask, I’m adding my nylon band. I suggest you try it for yourself and see how it works for you.

If you would like to read the research itself, it is posted as a pre-print on this medical site: https://www.medrxiv.org/content/10.1101/2020.04.17.20069567v2 as well as on the university’s website at: https://www.northeastern.edu/envsensorslab/wp-content/uploads/2020/04/FernandezMueller_PreliminaryReportFacemaskTestingProtocol_2020-04-17.pdf.

There are also more non-technical descriptions of the project and results available at: https://www.masktestingatnu.com and https://news.northeastern.edu/2020/04/20/pantyhose-toilet-paper-coffee-filters-which-materials-make-the-best-masks-to-stop-the-coronavirus/.

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