Originally published April 1, 2020.
HOMEMADE AND DIY FACE MASK GUIDELINES FOR USE
The outpouring of community support for medical personnel and those on the front lines of the coronavirus COVID-19 pandemic has been heartwarming. With news of personal protective equipment (PPE) shortages, including, face masks, gowns, and gloves among others, many non-healthcare businesses and individuals have sought to lend a hand to ease the burden on the medical community’s essential workers. In recent weeks, there has been growing interest in making homemade or do-it-yourself (DIY) face masks However, this well-intentioned endeavor does require an understanding of textile characteristics given the mechanism of viral spread as well as knowledge of the protective role a face mask plays. As both a healthcare professional who actively treats patients during this pandemic and an expert in functional textiles, there are a few salient points I would like to share with the general public and fellow healthcare workers relative to face masks.
COVID-19 is a type of highly-contagious infectious disease that many have seen images of resembling a sphere with surface projections similar to a crown. The size of these viral particles has been shown to be less than 1 micron. A 2020 Journal of Korean Medical Science study actually measured these particles to be as small as 70 to 80 nanometers, which is 0.7 to 0.8 microns. These viral particles are spread in the air from coughing or sneezing by those infected or from direct and indirect contact with the surfaces these particles land on.
Face masks have long been used by medical professionals. Most disposable surgical face masks are designed with the purpose of protecting medical staff and patients from cross-contamination from respiratory droplets from the medical professional. In other words, when a surgeon or dentist wears a surgical face mask during a procedure, they are preventing their respiratory droplets from speaking, breathing, coughing, or sneezing into the surgical field and contaminating the patient. Vice versa, a face mask can also protect the health care provider from a patient’s secretions as well. However, there are limits to how much various face masks can block the spread of particles, especially microscopic particles like viruses.
Out of an abundance of caution, people around the world have taken to crafting their own masks out of materials found in their homes. It is important to note that there are many factors to consider when it comes to making a face mask, but the materials and fit of the mask are key to its overall effectiveness.
For concerned citizens who want to make their own facemasks, here are a few points to keep in mind.
A 2013 Disaster Medicine and Public Health Preparedness study evaluated face masks made of different household materials to figure out how much each could filter particles. The study examined traditional disposable surgical masks, and face masks derived from T-shirts, dish towels, vacuum cleaner bags, silk, scarves, pillowcases, and linen materials. Traditional surgical face masks were shown to filter out about 97% of particles measuring 1 micron in size or larger, which is the size to consider for bacteria. Silk was the lowest performer filtering only 58% of particles measuring 1 micron, while cotton T-shirts ranged from 69% to 74% filtration depending on the composition of the T-shirt. Vacuum cleaner bags filtered the best out of household materials with 95% of particles measuring 1 micron filtered out. However, this same study found that breathability through vacuum cleaner bags was understandably the poorest.
Now, the real question is which household material should we use against viruses like COVID-19, which are below 1 micron in size? You can already see from the above numbers that household fabrics are pretty good at blocking larger particles but are still far from ideal, and even potentially less so for viruses. Looking at viruses smaller than 1 micron, studies have shown that surgical face masks block about 89% of particles, while face masks made from cotton T-shirts can be as low as 50% effective to block viral-sized particles. Moreover, even doubling the T-shirt material was found to increase the mask’s filtration effectiveness by only 1-2% more.
This is where my concern lies. There can be a false sense of security by using homemade or DIY face masks against viruses that can potentially place medical professionals at risk for the inadvertent spread of viruses either between or among medical personnel and infected patients. As such, N95 respirator masks should remain the best face mask for healthcare professionals on the front line treating COVID-19 patients directly. N95 masks are most protective against a virus as they can block 99% of particles around 1 micron and 95% of particles smaller than 0.3 microns. In the absence of N95 masks, standard surgical face masks are the next best option for these healthcare professionals.
So, what is the best role for homemade and DIY face masks for concerned individuals at home? Although they won’t replace an N95 or surgical mask, in these unprecedented times, homemade masks made of vacuum bags or doubling up on cotton t-shirts could indeed still be used in the place of standard surgical masks and N95 masks at home if needed by concerned citizens who are not in direct or regular contact with known COVID-19 patients, when standard surgical masks are not readily available or in regions with PPE shortages.