Abstract
Past studies on airborne spread of expiratory droplet nuclei between occupants were focused on long-term exposure under steady-state conditions. However, exposure during short-term events can be widely found in practice, e.g. medical examination or short meeting. Airborne transmission during short-term events under stratum ventilation was examined experimentally in this study. Two breathing thermal manikins were employed to simulate a standing infected person and a standing exposed person. The manikins were placed face-to-face and face-to-back to reproduce the exposure conditions with the highest and the lowest risk, respectively. Tracer gas was dosed into the air exhaled by the “infected” manikin to simulate the droplet nuclei. A newly developed average exposure index was used to evaluate the exposure risk. The time-averaged exposure index increases over time, but the increasing rate depends strongly on the duration of exposure time, e.g., the exposure index increases much faster during the first 5 minutes than during the period after 5 minutes. The exposure index during short-term events does not always decrease with the increase of separation distance. These findings imply that the control measures formulated based on steady-state conditions are not necessarily effective to short-term events.
Highlights
Infectious diseases such as influenza impair the health of infected people and cause medical expense burdens, increased absenteeism and decreased productivity, which result in economic losses [1][2]
There is still a need to consider the risk of airborne infection in case of short-term events, e.g., 10 min medical examination
The results revealed that in the case of face-to-face positioning, the distance between two persons should be longer than 1.0 m in order to have a relatively low exposure risk
Summary
Infectious diseases such as influenza impair the health of infected people and cause medical expense burdens, increased absenteeism and decreased productivity, which result in economic losses [1][2]. There is still a need to consider the risk of airborne infection in case of short-term events, e.g., 10 min medical examination. In this case, it takes time to reach the steady state and the dynamic interaction of breathing flows involving human plume evolves. The survival rate of some viruses decreases over time. It is important to investigate the dynamic exposure risk over time immediately after the droplet nuclei is being released
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
