Penetration and aerosolization of cough droplet spray through face masks: A unique pathway of transmission of infection

Abstract

The advent of the COVID-19 pandemic has necessitated the use of face masks, making them an integral part of the daily routine. Face masks occlude the infectious droplets during any respiratory event contributing to source control. In the current study, spray impingement experiments were conducted on porous surfaces like masks having a different porosity, pore size, and thickness. The spray mimics actual cough or a mild sneeze with respect to the droplet size distribution (20–500 [Formula: see text]) and velocity scale (0–14 [Formula: see text]), which makes the experimental findings physiologically realistic. The penetration dynamics through the mask showed that droplets of all sizes beyond a critical velocity penetrate through the mask fabric and atomize into daughter droplets in the aerosolization range, leading to harmful effects due to the extended airborne lifetime of aerosols. By incorporating spray characteristics along with surface tension and viscous dissipation of the fluid passing through the mask, multi-step penetration criteria have been formulated. The daughter droplet size and velocity distribution after atomizing through multi-layered masks and its effects have been discussed. Moreover, the virus-emulating particle-laden surrogate respiratory droplets are used in impingement experiments to study the filtration and entrapment of virus-like nanoparticles in the mask. Furthermore, the efficacy of the mask from the perspective of a susceptible person has been investigated.

Role of face masks and ventilation rates in mitigating respiratory disease transmission in ICU

“…To calculate the number of virions a healthy person inhales, the saliva volume should be estimated, which is accounted for by the number of droplets inhaled. From the droplets which are impacting the mask, some of the droplets whose kinetic energy is many folds higher than the dissipation energy of the droplets when impacted onto the mask will penetrate the mask and are inhaled by the healthy person 5 , 6 . To calculate the number of droplets penetrated, the mask data from the experimental study is utilized 6 , as shown in Table 4 , which specifies the penetration criteria of the droplets into the mask.…”

“…The droplet penetration length is reduced by when the emitter wears a face shield. Vadlamudi et al 5 analyzed the penetration and aerosolization of the cough droplets through the face mask to consider the effect of porous size, thickness, and porosity. They observed that all droplet sizes penetrate the face mask beyond a certain velocity.…”

Airborne influenza virus shedding by patients in health care units: Removal mechanisms affecting virus transmission

“…The surface tension for coughed droplets was initially set at 0.072 mN/m, the same as pure water, to reduce the number of calibration parameters. To assess the sensitivity of the results to changes in the surface tension, we varied this value based on the recent work of Vadlamudi et al, (2022) [78] who reported a surface tension of 0.0659 mN/m for coughed droplets. The results showed that within this range, changes to the surface tension value exhibited a negligible effect on the equilibrium diameter, and thus, a negligible effect on the settling efficiency.…”

Mechanism Study on the Alcoholysis and Polymerization Degree of Poly(vinyl alcohol) to Regulate Droplet Impact Behavior on Hydrophobic Surfaces

“…Droplet impact behavior has important research significance in inkjet printing, , aerospace, medicine, − agriculture, − and other fields. Especially, in the process of pesticide spraying, plant leaves exhibit hydrophobicity generated by multistage micro and nano structures and a variety of chemical components, resulting in the pesticide solution easily bouncing, tumbling, − gathering, and being lost when it hits the surface of plant leaves.…”