Experimental investigation of far‐field human cough airflows from healthy and influenza‐infected subjects

Dudalski, Nicholas; Mohamed, Ahmed S.; Mubareka, Samira; Bi, Ran; Zhang, Chao; Savory, Eric

doi:10.1111/ina.12680

Cited by 46 publications

(35 citation statements)

References 39 publications

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“…The initial velocity at t = 0 s is ∼4.0 m/s and then rapidly increases to 15.0 m/s at t = 0.03 s. The velocity gradually reduces to 4.0 m/s at time t = 0.08 s. The variation in the velocity qualitatively agrees with the results given by Gupta et al (2009) , Dudalski et al (2020) , and Kwon et al (2012) . However, Dudalski et al (2020) reported that the peak velocity value is ∼22.0 m/s at t = 0.068 s, which is different from the present result. A potential reason for the difference is that the position of the mouth and the onset time of coughing are slightly different among the volunteers in our experiments.…”

Section: Resultssupporting

confidence: 86%

The motion of respiratory droplets produced by coughing

Wang

Zhang

et al. 2020

Physics of Fluids

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Coronavirus disease 2019 has become a global pandemic infectious respiratory disease with high mortality and infectiousness. This paper investigates respiratory droplet transmission, which is critical to understanding, modeling, and controlling epidemics. In the present work, we implemented flow visualization, particle image velocimetry, and particle shadow tracking velocimetry to measure the velocity of the airflow and droplets involved in coughing and then constructed a physical model considering the evaporation effect to predict the motion of droplets under different weather conditions. The experimental results indicate that the convection velocity of cough airflow presents the relationship t −0.7 with time; hence, the distance from the cougher increases by t 0.3 in the range of our measurement domain. Substituting these experimental results into the physical model reveals that small droplets (initial diameter D ≤ 100 μ m) evaporate to droplet nuclei and that large droplets with D ≥ 500 μ m and an initial velocity u 0 ≥ 5 m/s travel more than 2 m. Winter conditions of low temperature and high relative humidity can cause more droplets to settle to the ground, which may be a possible driver of a second pandemic wave in the autumn and winter seasons.

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Section: Resultssupporting

confidence: 86%

The motion of respiratory droplets produced by coughing

Wang

Zhang

et al. 2020

Physics of Fluids

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“…With active breathing, sneezing and coughing, small droplets are formed, which consist of water, air, tiny particles (d p < 10 –6 m) and respiratory fluid. These components of human reflex processes have different rates and duration (time) of generation and, accordingly, lead to different effects on the environment and the human body 11 – 13 . The distance that these droplets can travel directly depends on the size of the droplets themselves and the speed of its propagation 14 – 16 .…”

Section: Introductionmentioning

confidence: 99%

A numerical assessment of social distancing of preventing airborne transmission of COVID-19 during different breathing and coughing processes

Issakhov

Zhandaulet

Omarova

et al. 2021

Sci Rep

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The spread of the novel coronavirus disease (COVID-19) continues to show that geographic barriers alone cannot contain the virus. Asymptomatic carriers play a critical role in the nature of this virus, which is rapidly escalating into a global pandemic. Asymptomatic carriers can inadvertently transmit the virus through the air stream. Many diseases can infect human bodies with tiny droplets or particles that carry various viruses and bacteria that are generated by the respiratory system of infected patients. This article presents the numerical results of the spread of droplets or particles in a room. The proposed numerical model in this work takes into account the sedimentation of particles or droplets under the action of gravitational sedimentation and transport in the room during the process of breathing and sneezing or coughing. Three different cases are numerically investigated taking into account normal breathing and coughing or sneezing, respectively, and three different rates of particle ejection from the mouth are considered. Navier–Stokes equations for incompressible flows were used to describe three-dimensional air flow inside ventilated rooms. The influence of ventilation rate on social distancing is also computationally investigated. It was found that particles can move up to 5 m with a decrease in concentration in the direction of the air flow. The conclusions made in this work show that, given the environmental conditions, the two meter social distance recommended by WHO is insufficient.

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“…Wang et al [ 35 ] measured the airflow velocity and droplets involved in exhaled cigarette smoke of coughs using PIV and reported the statistical relationship between velocity magnitude with time or coordinate. Dudalski et al [ 36 ] measured the far-field human cough airflows from healthy and influenza-infected subjects, and obtained the time variation of peak velocity in the center of airflow jet but did not discuss the velocity distributions. Wang et al [ 37 ] measured the velocity using PIV and captured droplets on a solid surface that subjects faced when coughing.…”

Section: Introductionmentioning

confidence: 99%

Measurements of exhaled airflow velocity through human coughs using particle image velocimetry

Han

Ooka

Kikumoto

et al. 2021

Building and Environment

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The sudden outbreak of coronavirus (COVID-19) has infected over 100 million people and led to over two million deaths (data in January 2021), posing a significant threat to global human health. As a potential carrier of the novel coronavirus, the exhaled airflow of infected individuals through coughs is significant in virus transmission. The research of detailed airflow characteristics and velocity distributions is insufficient because most previous studies utilize particle image velocimetry (PIV) with low frequency. This study measured the airflow velocity of human coughs in a chamber using PIV with high frequency (interval: 1/2986 s) to provide a detailed validation database for droplet propagation CFD simulation. Sixty cough cases for ten young healthy nonsmoking volunteers (five males and five females) were analyzed. Ensemble-average operations were conducted to eliminate individual variations. Vertical and horizontal velocity distributions were measured around the mouth area. Overall cough characteristics such as cough duration time (CDT), peak velocity time (PVT), maximum velocities, and cough spread angle were obtained. The CDT of the cough airflow was 520–560 m s, while PVT was 20 m s. The male/female averaged maximum velocities were 15.2/13.1 m/s. The average vertical/horizontal cough spread angle was 15.3°/13.3° for males and 15.6°/14.2° for females. In addition, the spatial and temporal distributions of ensemble-averaged velocity profiles were obtained in the vertical and horizontal directions. The experimental data can provide a detailed validation database the basis for further study on the influence of cough airflow on virus transmission using computational fluid dynamic simulations.

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Experimental investigation of far‐field human cough airflows from healthy and influenza‐infected subjects

Cited by 46 publications

References 39 publications

The motion of respiratory droplets produced by coughing

The motion of respiratory droplets produced by coughing

A numerical assessment of social distancing of preventing airborne transmission of COVID-19 during different breathing and coughing processes

Measurements of exhaled airflow velocity through human coughs using particle image velocimetry

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