Research Article
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Published Online: 30 January 2009

The Size Distribution of Droplets in the Exhaled Breath of Healthy Human Subjects

Publication: Journal of Aerosol Medicine
Volume 10, Issue Number 2


Droplets carried in exhaled breath may carry microorganisms capable of transmitting disease over both short and long distances. The size distribution of such droplets will influence the type of organisms that may be carried as well as strategies for controlling airborne infection. The aim of this study was to characterize the size distribution of droplets exhaled by healthy individuals. Exhaled droplets from human subjects performing four respiratory actions (mouth breathing, nose breathing, coughing, talking) were measured by both an optical particle counter (OPC) and an analytical transmission electron microscope (AEM). The OPC indicated a preponderance of particles less than 1 μ, although larger particles were also found. Measurements with the AEM confirmed the existence of larger sized droplets in the exhaled breath. In general, coughing produced the largest droplet concentrations and nose breathing the least, although considerable intersubject variability was observed.

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cover image Journal of Aerosol Medicine
Journal of Aerosol Medicine
Volume 10Issue Number 2Summer 1997
Pages: 105 - 116
PubMed: 10168531


Published online: 30 January 2009
Published in print: Summer 1997


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