Efficacy of homemade face masks against human coughs: Insights on penetration, atomization, and aerosolization of cough droplets

Krishan, B and Gupta, D and Vadlamudi, G and Sharma, S and Chakravortty, D and Basu, S (2021) Efficacy of homemade face masks against human coughs: Insights on penetration, atomization, and aerosolization of cough droplets. In: Physics of Fluids, 33 (9).

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Abstract

Ever since the emergence of the ongoing COVID-19 pandemic, the usage of makeshift facemasks is generally advised by policymakers as a possible substitute for commercially available surgical or N95 face masks. Although such endorsements could be economical and easily accessible in various low per-capita countries, the experimental evidence on the effectiveness of such recommendations is still lacking. In this regard, we carried out a detailed experimental investigation to study the fate of a large-sized surrogate cough droplet impingement at different velocities (corresponding to mild to severe coughs) on various locally procured cloth fabrics. Observation shows that larger ejected droplets (droplets that would normally settle as fomites in general) during a coughing event have enough momentum to penetrate single-layer cloth masks; the penetrated volume atomize into smaller daughter droplets that fall within aerosol range, thereby increasing infection potential. Theoretically, two essential criteria based on the balances of viscous dissipation-kinetic energy and surface tension-kinetic energy effects have been suggested for the droplet penetration through mask layers. Furthermore, a new parameter called η (the number density of pores for a fabric) is developed to characterize the volume penetration potential and subsequent daughter droplet size. Finally, the effect of mask washing frequency is analyzed. The outcomes from the current study can be used as a guide in selecting cloth fabrics for stitching multi-layered. © 2021 Author(s).

Item Type:	Journal Article
Publication:	Physics of Fluids
Publisher:	American Institute of Physics Inc.
Additional Information:	The copyright for this article belongs to Authors
Keywords:	Aerosols; Clothes; Kinetic energy; Kinetics, Daughter droplets; Droplet impingement; Experimental evidence; Experimental investigations; Kinetic energy effects; New parameters; Number density; Viscous dissipation, Drops
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology Division of Interdisciplinary Sciences > Centre for Biosystems Science and Engineering Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	03 Dec 2021 08:26
Last Modified:	03 Dec 2021 08:26
URI:	http://eprints.iisc.ac.in/id/eprint/70197

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