Applications of an Exhaled Breath Aerosol Monitoring System
Date Issued
2011
Date
2011
Author(s)
Lin, Wan-Ting
Abstract
Coughing and sneezing are known to spread respiratory diseases. The aerosol outputs by coughing and sneezing are visible because of the high number concentration and large micro-metered size. Coughing and sneezing can be loud and irritating to people around, which is good because it alerts people to stay away. In contrast to these audible and visible aerosol generation mechanisms, several recent studies reported that “silent” tidal breathing can also generate aerosols. This might play a more important role in disease transmission, especially in intensive care and emergency care units. Two aerosol generation mechanisms were proposed in previous studies: the turbulence induced aerosolization and the Bronchiole Fluid Film Burst (BFFB). The main objectives of the present study were (1) to verify the proposed lung aerosol generation mechanisms, (2) to study the dependency of exhaled breath aerosol on breathing pattern and other lung function variables, and (3) to characterize the differences in exhaled breath aerosols between healthy and sick conditions of the same subjects.
The results supported the hypothesis of BFFB through a breath-holding technique. The EBA (Exhaled Breath Aerosol) count per breath increased with increasing tidal volume. However, breathing frequency did not affect EBA generation. We speculated that this is due the number of closing-up and re-opening terminal bronchioles increased with increasing tidal volume. This number apparently is independent of breathing frequency. The between-subject variation is much higher than the within-subject variation, indicating that the mucus properties and the respiratory tract structure vary more significantly among subjects. The EBA of all tested subjects showed similar size distribution, with a count median diameter of 0.3 micrometer and GSD of 2.4. When subjects were sick, they tended to generate more exhaled breath aerosols, showing 20 to 50% increase in count per breath, a bad news to health-care workers.
Subjects
exhaled particle
tidal volume
pulmonary function
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