Study on the initial velocity distribution of exhaled air from coughing and speaking

Abstract

Increasing concerns about the spread of airborne pathogens such as severe acute respiratory syndrome (SARS) and novel swine-origin influenza A (H1N1) have attracted public attention to bioaerosols and protection against them. The airborne pathogens are likely to be expelled from coughing or speaking, so the physical data of the exhaled particles plays a key role in analyzing the pathway of airborne viruses. The objective of this study was to analyze the initial velocity and the angle of the exhaled airflow from coughing and speaking of 17 males and 9 females using Particle Image Velocimetry (PIV) and acrylic indoor chamber. The results showed that the average initial coughing velocity was 15.3 m/s for the males and 10.6 m/s for the females, while the average initial speaking velocity was 4.07 m/s and 2.31 m/s respectively. The angle of the exhaled air from coughing was around 38° for the males and 32° for the females, while that of the exhaled air from speaking was around 49° and 78° respectively. Also, the linear relation between the tested subject's height and their coughing and speaking velocity was shown in this study.

Enhanced spread of expiratory droplets by turbulence in a cough jet

“…The mouth opening area was almost constant during the cough period, at about 4±0.95 cm 2 for males and 3.37±1.4 cm 2 for females [29]. A recent study by Kwon et al [30] showed that the average coughing velocity is 15.3 m/s for males, and 10.6 m/s for females.…”

“…The airflow in buildings is designed to be less than 0.25 m/s for thermal comfort [28]. The jet speed of coughing and breathing can be 6e22 m/s (over 10 m/s on average) and 1e5 m/s respectively [13,29,30]. The transport of the expiratory droplets can be considered as two stages, with the primary being coughing/exhalation jet transport, followed by the secondary, dispersion by room airflow.…”

Human Cough as a Two-Stage Jet and Its Role in Particle Transport

“…A maximum velocity range of 6–28 m/s has been detected, and the cough was found to expand linearly in the initial stage [6, 7, 11–13]. Tang [14] estimated the maximum velocity to be 8 m/s using the Schlieren imaging technique.…”

Particle image velocimetry measurement of indoor airflow field: A review of the technologies and applications

“…The average expiration air velocity was 11.7m/s for coughing and 3.9m/s for speaking. Similarly, the initial velocity and angle of exhaled airflow from coughing and speaking was measured with 26 tested subjects using PIV by Kwon et al [68]. VanSciver et al [69] also applied PIV system to measure the velocity field of human cough from 29 subjects.…”