Exhaled Jet and Viral-Laden Aerosol Transport from Nasal Sneezing

Hana Salati,Kazuhide Ito,Sara Vahaji,Jingliang Dong,David F Fletcher,Mehrdad Khamooshi,Kiao Inthavong

doi:10.4209/aaqr.210338

Hana Salati, Kazuhide Ito + Show 5 more

Open Access

https://doi.org/10.4209/aaqr.210338

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Abstract

The recognition that the spread of COVID-19 is primarily through airborne transmission has brought renewed urgency to understand the spread of aerosols generated from patients. Viral-laden aerosols generated from oral coughs have been well studied; however, aerosols generated from nasal sneezing has been overlooked. This scenario arises from patients who suffer allergenic rhinosinusitis, or the nasal cavity is irritated, particularly during naso-endoscopy. Nasal sneezing is characterised by an explosive blast of air exiting the nostrils, which can be considered as dual jets, resulting in the spread of viral-laden aerosols remaining suspended in the air. This study used computational fluid dynamics consisting of a hybrid RANS-LES turbulence method to model the airflow and the discrete phase model to track aerosol dispersion during nasal sneezing. The results demonstrated that the exhaled airflow jets during nasal sneezing resemble the flow characteristics of two parallel jets in co-flow. These two jets interfere with each other in the merging zone, and after they merge, the sneeze plume expands radially. The nasal sneeze forms a V-shaped plume with smaller particles in the core region. At the end of the sneeze, when the exhaled jets have lost their initial momentum, the large particle dispersion is dominated by gravity. We detected the presence of a ‘sneeze puff’ that transport droplets away from the body, similar to the buoyant puff observed in recent COVID-19 studies of oral coughs.

Highlights

It is widely accepted that the spread of COVID-19 is highly transmissible by airborne transmission, arising through the inhalation of viral-laden aerosols exhaled through coughing or sneezing from an infected person (Arumuru et al, 2020; Diwan et al, 2020)
The results demonstrated that the exhaled airflow jets from the nostrils move downwards and impinge on the respirator's internal surface
The nasal sneeze jets pass over the curved upper lip surface, and boundary layer separation occurs, which can be seen in the right nostril plane (Fig. 3(C))

Summary

Introduction

It is widely accepted that the spread of COVID-19 is highly transmissible by airborne transmission, arising through the inhalation of viral-laden aerosols exhaled through coughing or sneezing from an infected person (Arumuru et al, 2020; Diwan et al, 2020). Aerosols exhaled through coughing, sneezing, talking, and breathing by an infected person introduces an inhalation exposure risk to nearby people for respiratory infection. Direct close contact of large particles produced by coughing or sneezing is approximately one meter (Leder and Newman, 2005; Morawska, 2005), while aerosols introduced by sneezing and coughing can travel for 7–8 meters (Bourouiba, 2020). Aerosols from an infected person can be generated from oral coughs (Johnson et al, 2011), singing (Bahl et al, 2021), and exhalation (Philip et al, 2021). An overlooked scenario is aerosol generation from nasal sneezing despite how common allergenic rhinosinusitis is among the general population. When the nasal cavity is irritated, such as during naso-endoscopy, or inflamed, the nose experiences a tickly, itchy sensation leading to sneezing

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