Types of masks N95 respirator masks : These masks fit tightly to the face and have the highest filtration efficiency, blocking 95 percent of particles of 0.3 microns or larger. An N95 mask protects medical workers who come into contact with high doses of the virus while visiting and carrying out medical procedures on multiple patients. The rest of us don’t need that level of protection, so these masks should be
reserved for health care workers only . To learn more about how these masks work, check out this video animation from the Arizona State University Risk Innovation Lab.
VIDEO Medical masks : These are also in short supply and should be used only by medical workers. Sometimes called
surgical masks or procedure masks , these masks are those rectangular shaped coverings (often pleated) that come with elastic ear loops. Medical masks are made of a paper-like nonwoven material and are often given to a coughing patient waiting to see a doctor. Compared to the N95 mask, a medical mask filters about 60 to 80 percent of particles and,
according to the Food and Drug Administration , mostly blocks “large-particle droplets, splashes, sprays or splatter that may contain germs.”
Homemade fabric masks : The Centers for Disease Control and Prevention recommends we cover our faces with a scarf or homemade fabric mask when we are in public. The effectiveness of homemade masks varies depending on the fabric used, the style and the fit.
In laboratory tests , some homemade masks did a poor job, while others rivaled the filtration of a medical mask. In another study,
21 people made their own masks out of T-shirts, and researchers compared the homemade masks to medical masks. “Both masks significantly reduced the number of microorganisms expelled by volunteers,” although surgical masks were better, wrote the study authors. In community studies, homemade masks were found to offer some protection during viral outbreaks.
You can sew a mask using a number of mask patterns circulating on the internet or try a no-sew pattern. We’ve included links to both in this guide, under “How to make a mask,” below.
Picking a material to make your own mask Remember, any face covering is better than no face covering . While some people are experimenting with homemade masks using air filters and vacuum bags, the average person doesn’t need that level of protection if you’re practicing social distancing and leaving the house only for essentials. Given that there is so much variability in fabrics, the best advice is to start with a light test. Hold the fabric or mask up to the light and see how much light gets through. The tighter the weave, the less light you’ll see, and the more protection you’ll get. Test the fabric over your face to make sure you can still breathe through it, though.
Because of a shortage of masks, aerosol scientists around the country have been testing everyday materials to see how well they might work in a homemade mask. Most of the time, they have compared the amount and size of particles filtered to the standard used for medical masks — 0.3 microns. However, an often-cited 2013 study from the University of Cambridge used a different standard, testing two layers of materials using particles of about 1 micron. Linsey Marr, an aerosol scientist at the University of Virginia, notes that while the 0.3-micron test is a higher standard, the 1-micron test still can be useful in helping people make decisions about mask materials. “There are probably a lot more viruses in 1-micron droplets/aerosols than in 0.3-micron droplets/aerosols,” said Dr. Marr. “So even if a mask only removes 20% of the droplets/aerosols that are 0.3 microns in size, it probably does better with the 1-micron droplet/aerosols, materials testing.”
Here’s a look at some of the everyday products that have been studied for homemade masks. You can find more information in our story,
What’s the Best Material for Mask ?
T-shirts : Most of us have an old T-shirt we could cut up into a no-sew mask. It’s one of the most convenient fabrics to use, but there is a lot of variability in how well T-shirt material performs in lab tests. At the University of Virginia, a single-layer of an old cotton T-shirt captured 20 percent of particles down to 0.3 microns. It captured 50 percent of particles down to 1 micron. A 2013 University of Cambridge study tested two layers of T-shirt
which captured about 70 percent of particles down to 1 micron.
Cotton quilting fabric : This is the high-thread-count cotton fabric preferred by quilters for its durability. In studies at
Wake Forest Baptist Health , masks made with quilting fabric rivaled the filtration efficiency of surgical masks.
Tea towels: Tea towels became a popular source of mask material after
an August 2013 study from researchers at the University of Cambridge found the material compared well to a medical mask at the 1-micron particle size. The study authors did not note the brand. The towel used was not terry cloth, but the tightly-woven absorbent tea towel variety.
Pillowcases : Pillowcases are a good option for sewers who don’t have other fabric. In the 2013 study, 2 layers of pillowcase fabric tested close to the efficiency of a surgical mask at the 1-micron standard, but in a
study at Missouri University of Science & Technology , it took four layers of 600-thread-count pillowcase material to achieve that level of protection at the 0.3-micron standard.
Flannel pajamas : A two-layer mask of flannel and cotton was one of the best tested in the Wake Forest Baptist study and rivaled the efficiency of a surgical mask.
Coffee filters and paper towels : The C.D.C. suggests inserting a coffee filter into your mask for extra protection. Missouri University of Science & Technology scientists found that using three coffee filters made it difficult to breathe. Adding a layer of paper towel in between two layers of fabric could make your homemade mask more efficient. An engineer at an air purifier firm ran his own test and found a single paper towel filters 23 percent of 0.3 microns and two paper towels filtered 33 percent. We added a paper towel to our homemade T-shirt mask.
Scarves and bandannas : When it comes to ease of use, you can’t beat a scarf or bandanna to cover your face. But bandannas are thin and, even folded over four times, don’t offer much protection. Scarves may be better but can be thick and hot. Both are better than nothing.
Filters and vacuum bags : Scientists trying to find effective alternatives for medical workers have cut up layers of air filters and tested HEPA vacuum bags. Both can work quite well, but both have significant downsides. Air filters, when cutting up, can release fibers that can be dangerous to inhale, so the filter material should be sandwiched between layers of heavy cotton fabric if used in a mask. Vacuum bags are good filters but not that breathable. Plus, some brands of vacuum bags may contain fiberglass so it should not be used to cover your face.
How to make a mask You can find a variety of sewing patterns and no-sew mask ideas online. The U.S. Surgeon General has created a video for an easy no-sew mask.
VIDEO People have made no-sew masks out of stretchy boxer shorts ▼ and,
VIDEO two folded paper towels ▼.
VIDEO Jiangmei Wu , a
paper artist and assistant professor of interior design at Indiana University,
offers a pattern for making a paper mask , as shown in this video. Or
try this ninja mask a mom made for her son with a long-sleeved T-shirt. The
Mask4All website also has several mask ideas.
If you can sew,
The Times Style section has provided instructions for a simple mask pattern that can be downloaded.
How to Take Care of a Mask Now that you’ve got a mask, you need to take care of it. Here’s some advice about washing and reusing your mask.
Can I reuse my medical mask? Medical masks and N95 masks should be saved for medical workers, but if you have a medical mask, you should know that it was designed for one-time use. However, a number of scientists, led by
a group at Stanford University , are studying the best way to sanitize masks to extend the life of the personal protective equipment used by medical workers during the current shortage.
The problem is that washing or sanitizing a medical mask will degrade it, making it less effective.
Scientists have found that using UV light, heat and humidity or a hydrogen peroxide vapor could work, but the methods are developed for use in hospitals with special equipment and are not for home use. You can learn more in our story about
efforts to decontaminate thousands of medical masks .
“I would be wary of putting them in the oven because of the potential to reach too high a temperature and melt the plastic fibers, thus damaging the mask,” said Linsey Marr, a leading aerosol scientist at the University of Virginia who has been studying ways to extend the life of medical masks. “Studies on other viruses show inactivation at about 150 degrees Fahrenheit, which is lower than many ovens can go. But that’s with high humidity, and the humidity makes a big difference. If you have an oven that can hit 150 degrees and you put a pan of water in there, this could be effective, but nobody has tested the method on this specific virus.”
If you have multiple masks, the best strategy is to rotate the use of the masks over several days, which gives time for the virus to die. For medical workers,
one strategy is to keep a set of five masks , so they can wear a new mask every day and return to the first mask on the sixth day.
“The safest thing to do might be to put the mask somewhere safely out of reach,” said Dr. Marr. “Over a few days, the viruses should decay. In fact, studies have found that viruses usually decay faster on fabric and other porous materials than on hard materials like steel or plastic.”
How do I care for my fabric mask? It’s much easier to clean a fabric mask than a medical mask. The C.D.C. says fabric masks should be “
washed routinely .” The mask experts I spoke with wash theirs daily in a machine or a sink, just using regular laundry soap. You can use the dryer or let it air dry. Although it’s not necessary, you can also go over it with a hot iron for a full assault on any germs that might remain.
Just as with a medical mask, chemicals like bleach or hydrogen peroxide will begin to degrade the fabric fibers, making the maskless effective. Dr. Marr notes that a virus can’t replicate outside the body, and if virus particles have been trapped by the mask, they are pretty well stuck there and will decay or be removed during washing.
“Washing with soap and water should work,” Dr. Marr said. “I throw my cloth mask in the washing machine with the rest of the laundry and dry it on low heat. I would avoid bleach because we know that it can degrade fibers. The important thing is to avoid damaging the fibers in the mask.”
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