Halloween has long offered an endless variety of mask options from ghouls and goblins to superheroes and superstars. COVID 19 seeks to challenge Halloween in regards to its preponderance of mask types and stretch the mask out to practically year long use. Halloween must be jealous as COVID sports a variety of materials and designs striving for functionality and fashion.
Neither Halloween nor COVID 19 requires any introduction or explanation. Masses of children and many adults dress up yearly to celebrate a mass candy binge for one. Even greater masses of all ages now face the new face covering requirements with a variety of emotions as they seek to avoid contagion, condemnation, or loss of comfort for the other. With COVID, the fashion portion is up to the individual, but functionality involves more science than preference. With a shortage of the high end N95 type masks and a plethora of do-it-yourselfers employing every material possible, what are your options?
Before examining the science behind the different materials available to make masks, lets address another practical question. Are they even necessary? It depends on the goal one is seeking. Are you aiming to protect yourself or protect others? If as an individual or as a collective society, the goal is simply to protect the person wearing the mask, the mask can have different performance characteristics than one which is intended to prevent spread from the viral carrier. For example, the study to be described below looked about the ability of different material to prevent a simulated cough or sneeze from pushing the virus through different material. This physics test concerns the ability of a viral carrier from spreading the virus through a mask. Breathing in air through a mask will not be a high speed event.
If the goal is to limit the virus from leaving an infected person, and spreading to those close by, the requirements for a good material are different. What works at low speed breathing does not always work for high speed coughs and sneezes. This study looks more at this latter type of functionality but admits that they do not factor in another important factor: the mask fit. A wonderfully protective material can be bypassed if air leaks out of gaps in the mask fitting to the face or through a valve which allows air to expel.
Two other aspects of the necessity question also demand attention. First, are we as a society overreacting? Many debate whether the danger deserves this response. Many assert that the hysteria of COVID 19 has been exaggerated and propagandized. Second, even if the virus deserves such a big response, could we respond in more effective ways that mask mandates? Many doubt that masks are as effective as their promoters proclaim and argue that other societal responses would work better. These questions are not addressed by the study nor the group whose website is announcing the study.
With all those caveats and debates out of the way, the study reported what should be obvious: Different mask materials work better than others. That is no shocker. The question then arises, which fabrics are better? Not surprisingly, N95 respirator masks and surgical masks were near the top of the list. Interestingly, HEPA vacuum bags adapted for masks outperformed these medical masks and some multi-layered masks performed as well or sometimes better than the medical masks. The article at the link below provides the full chart comparing all the fabrics and multi-layered combos they tested.
To produce these results, the experimenters pulled air at a set speed through a pipe while adding particles of similar size to the coronavirus and measuring the concentration. The pipe was fitted with a section in which the test material covered the pipe opening. The concentration of particles exiting the other side of the material was tested by other particle detectors. The efficacy of the material to filter the given particles was calculated by the percentage lower concentration produced.
Rather than just basing all decisions on this test method, they also compared the ease of breathing through the materials and tested the same materials while damp. The breathability test used subjective ratings by actual people during calm and then during rapid breathing. For the damp testing, they added the amount of moisture typically exhaled by an adult in 1 hour of normal respiration.
For those with any interest in masks for COVID 19, this is a study you should read in its entirety and save for later referencing. It is relatively short and straightforward. For those just wanting the highlights, here you go: 1) Not all mask materials are created equal (look at article graph for which is better); 2) Materials matter only when masks fit the face; 3) Even the best masks are not perfect and only remove a percentage of the particles; 4) We need more science; 5) We need more people to use common sense in regards to both personal mask use and societal responses.
In preparing for 2020 and beyond, you must inform yourself and contribute to the conversation. Be a part of a movement to build discerning wisdom in yourself and others.
Eugenia O’Kelly, Sophia Pirog, James Ward, P John Clarkson. Ability of fabric face mask materials to filter ultrafine particles at coughing velocity. BMJ Open, 2020; 10 (9): e039424 DOI: 10.1136/bmjopen-2020-039424
Thanks to Science Daily:
University of Cambridge. “Study measures effectiveness of different face mask materials when coughing.” ScienceDaily. ScienceDaily, 29 October 2020. <www.sciencedaily.com/releases/2020/10/201029082208.htm>.
Face Mask Research Website (not affiliated with SFM):
see upcoming mini blogs for my thoughts on this site.