Textile Masks and Surface Covers – A ‘Universal Droplet Reduction Model’ Against Respiratory Pandemics

Abstract

<jats:p>The main form of COVID-19 transmission is via oral-respiratory droplet contamination (droplet; very small drop of liquid) produced when individuals talk, sneeze or cough. In hospitals, health-care workers wear facemasks as a minimum medical droplet precaution to protect themselves. Due to the shortage of masks during the pandemic, priority is given to hospitals for their distribution. As a result, the availability/use of medical masks is discouraged for the public. However, given that asymptomatic individuals, not wearing masks within the public, can be highly contagious for COVID-19, prevention of environmental droplet contamination (EnDC) from coughing/sneezing/speech is fundamental to reducing transmission. As an immediate solution to promote public droplet safety, we assessed household textiles to quantify their potential as effective environmental droplet barriers (EDBs). The synchronized implementation of a universal community droplet reduction solution is discussed as a model against COVID-19. Using a bacterial-suspension spray simulation model of droplet ejection (mimicking a sneeze), we quantified the extent by which widely available clothing fabrics reduce the dispersion of droplets onto surfaces within 1.8m, the minimum distance recommended for COVID-19 social distancing. All textiles reduced the number of droplets reaching surfaces, restricting their dispersion to &lt;30cm, when used as single layers. When used as double-layers, textiles were as effective as medical mask/surgical-cloth materials, reducing droplet dispersion to &lt;10cm, and the area of circumferential contamination to ~0.3%. The synchronized implementation of EDBs as a community droplet reduction solution (i.e., face covers/scarfs/masks &amp; surface covers) could reduce EnDC and the risk of transmitting or acquiring infectious respiratory pathogens, including COVID-19.</jats:p>

Nonmedical Masks in Public for Respiratory Pandemics: Droplet Retention by Two-Layer Textile Barrier Fully Protects Germ-free Mice from Bacteria in Droplets

“… a ) Spray-droplet simulation model using bacterial aqueous solution recently validated for the assessment of textiles against COVID-19 in our laboratory. Unmodified from by Rodriguez-Palacios et al 11 ; open access license. Inset, mechanism of passive filtration.…”

“…All respiratory viruses need liquid suspensions/droplets to remain infective for long periods of time (vs. dry), and to contaminate susceptible individuals 12 . Therein, using a bacterial-suspension spray simulation model of droplet ejection (mimicking a sneeze) 11 , and a Parallel Lanes Plating method 13 , herein we quantified the extent by which widely available clothing fabrics could protect germ-free animals on the other side of the textile-barrier (simulating a properly worn mask) from contamination by the microbes contained in micro-droplets. In short, the reported experiment was conducted with eighteen 9-week-old germ-free (Swiss Webster) mice (males:females, 1:1), which were individually allocated to 18 germ-free cages, for repeated exposure to a cloud of micro-droplets.…”

“…To test the textile barrier as an effective surrogate alternative simulating a medical mask, we used two layers of a widely common household textile (100% combed-cotton, T-shirts) as cage lid/cover, instead of using the standard germ-free grade mouse cage lids 14 . The choice of textile material was based on their recently proven effect in retaining droplets 11 . Our earlier studies have also shown that two layers of passive filtration are fully protective against viruses/microbes in the room air, when germ-free mice are raised under two-layer of such nested filtration 14 .…”

“…Because the voluntary use of masks within the community is expected to cause social polarization (believers vs. non-believers; including presidential leaders 10 ), if not made mandatory, there is need of further convincing evidence of the ‘mask-wearing’ benefits to incentive their use in public. To prevent the contamination of the environment with COVID-19 droplets, as a continuation of previous studies in masks 11 , and to promote effective education/communication initiatives, herein, we conducted studies using animals born and maintained for life with no germs (germ-free) to determine how effective household textiles are as barriers to protect against microbes inside the droplets.…”

Transmission of SARS-CoV-2 and Other Infections at Large Sports Gatherings: A Surprising Gap in Our Knowledge

“…If sports competitions are resumed in the near future, we strongly believe that all matches should be held behind closed doors, paying special attention to gatherings in crowded places that could potentially occur in the immediate vicinity of stadiums. Should this not be possible, we believe that the use of face coverings as a means of source control, while not a substitute for social distancing which anyway cannot be maintained at large gatherings, should be made mandatory for spectators, given recent evidence supporting their role in reducing the transmission of the infection (14,15). In addition, the implementation of intensified surveillance of those attending such events, at least for the immediate future, should be considered as a means of learning more about the dynamics of transmission of this disease and supporting tracking and containing infections (10,16).…”