Community masks — Prosthodontics, Special Patient Care, Maxillofacial Prosthetics, and Weintraub Center, UCLA School of Dentistry

Simple masks that can protect yourself

As of April 3rd, 2020, it is advised by the CDC and the US Surgeon General for the public to use simple cloth face coverings in social settings where social distancing is difficult to maintain (such as in stores), especially in areas of significant community-based transmission in order to slow down the spread of the virus. In response to the recommendation, Riverside, Los Angeles, San Diego County and counties in San Francisco urged their residents and essential workers to wear facial coverings in public. The California Department of Public Health, Los Angeles County Department of Public Health (PDF) and the Office of Los Angeles Mayor Eric Garcetti have also issued guidance suggesting cloth face coverings can reduce the potential transmission from infected but asymptomatic individuals. As critical PPE such as N95 and surgical masks are in high-demand by healthcare workers, cloth face coverings can be made with available household materials and can be used as an additional public health measure.

Some people opt to add an additional filter, such as HEPA vacuum bag filters, polypropylene filters or coffee filters, inside their homemade masks as an extra protective layer to mimic the N95 masks. Dr. Dalai from Stanford emphasized that filters should be replaced often and the placement of the filter is very important. Filters must be sandwiched between two layers of fabric (cotton, silk or nylon) to prevent the inhalation of filter materials. It is also important to ensure the filter fabric does not contain a high amount of fiber and other synthetic materials since the inhalation of glass fiber can cause respiratory problems. The fabric materials should allow unobstructed breathing, and they do not saturate easily with moisture.

To determine which household items performed best, researchers from Cambridge University measured materials at the 0.02 um level, which is six times smaller than the 0.125 um size of COVID-19 viral particles. Most homemade masks were able to capture at least 50% of the virus particles, with the best performers being the vacuum cleaner bag (86%), dish towel (73%), and cotton blend shirt (70%). Furthermore, certain materials were found to have increased filtration efficiency when doubled, such as the dish towel which gains an extra 14% efficiency. Other materials when doubled, such as 100% cotton T-shirts and pillowcases only gain 1-2% increase in filtration efficiency. Lastly, this study ultimately recommends the use of a pillowcase or 100% cotton T-shirt as a mask material despite the lower increased filtration. This is because the vacuum bag and doubled dish towel breathability was significantly harder than that of a surgical mask and was deemed impractical.

Communities are making masks to support local hospitals

Given the massive shortage of supplies of critical PPE, many communities have been actively working with healthcare networks and producing homemade masks to support local hospitals. Although these masks may not replace the N95 masks, they are still very helpful for hospitals that are running out of supplies.

For safety reasons, avoid making masks if one is sick, and all mask makers should perform proper hand hygiene beforehand. In general, masks should be light-colored latex-free and should use 100% cotton, polyester thread material, and two layers of fabric. Be sure to check the specific hospital’s community and city guidelines, as it may vary from hospital to hospital. Below are some useful instructions on how to make such masks:

CDC

City of Los Angeles