While getting a pair of nylons is pretty easy (for now), questions remain in the public’s mind about the best material for a homemade mask. Here are some tips from mask researchers. Use a thick-weave cotton: In general, thicker, high-grade cotton masks tend to do a better job of filtering out small particles, says Dr. Scott Segal, a professor and chair of anesthesiology at Wake Forest School of Medicine who has been putting various cloth masks to the test since March. His rule of thumb: Hold up the fabric to a bright light or to the sun. If “you can see the light outlining the individual fibers in the fabric, it’s probably not a good filter. And if you can’t, it’s probably going to filter better.” Thin T-shirt material didn’t do a great job in his testing, though “probably anything is better than nothing,” he says. Thicker, heavier-weight T-shirts would probably be better filters, he adds.
Layer your fabric: Cloth masks made from multiple layers seem to do a better job than single-layer ones, says Yang Wang, an assistant professor of environmental engineering at Missouri University of Science and Technology who studies how fine particles like aerosols are transmitted and has been testing how various household items hold up as mask materials. A single-layer mask made from a 400-thread-count pillowcase had a filtration efficiency of around 10%, but if you bumped it up to four layers of cloth, the efficiency went up to around 20%. “It’s not ideal, but by using more layers, you can bump up the filtration efficiency,” Wang says just make sure not to use so many layers that you can’t breathe.
When Should a Mask Be Used?
Face masks should be used only by individuals who have symptoms of respiratory infection such as coughing, sneezing, or, in some cases, fever. Face masks should also be worn by health care workers, by individuals who are taking care of or are in close contact with people who have respiratory infections, or otherwise as directed by a doctor. Face masks should not be worn by healthy individuals to protect themselves from acquiring respiratory infection because there is no evidence to suggest that face mask worn by healthy individuals are effective in preventing people from becoming ill. Face masks should be reserved for those who need them because masks can be in short supply during periods of widespread respiratory infection. Because N95 respirators require special fit testing, they are not recommended for use by the general public.
There are 2 main types of masks used to prevent respiratory infection: surgical masks, sometimes referred to as face masks, and respirators. These masks differ by the type and size of infectious particles they are able to filter. Face masks are used more commonly for respiratory viruses that spread via droplets, which travel short distances and are transmitted by cough or sneeze. Face masks often fit loosely and prevent the wearer from spreading large sprays and droplets, as well as preventing hand-to-face contact. N95 respirators block 95% of airborne particles. They are tight fitting and prevent inhalation of smaller infectious particles that can spread through the air over long distances after an infected person coughs or sneezes. Diseases that require use of an N95 respirator include tuberculosis, chickenpox, and measles. N95 respirators cannot be used by individuals with facial hair or by children because it is difficult to achieve a proper fit. In those cases, a special respirator called a powered air-purifying respirator may be used instead.
Conclusion
If wearing a face mask is indicated, it is important to wash your hands with soap and water for at least 20 seconds prior to putting on the face mask. An alcohol-based sanitizer that contains at least 60% alcohol can also be used if soap and water are unavailable.
