Open Access
Droplets expelled during human expiratory activities and their origin
Lidia Morawska,Graham R. Johnson,Zoran Ristovski,Megan Hargreaves,Kerrie Mengersen,Christopher Y.H. Chao,Man Pun Wan,Yuguo Li,Xaiojan Xie,David Katoshevski +9 more
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TLDR
It is found that the time taken for expiratory droplets to achieve short term equilibrium is comparable to that for pure water droplets and that the droplet size distributions have distinct features reflecting specific production mechanisms whose intensity varies with the nature of the activity.Abstract:
This paper presents the findings of the most comprehensive program of study to date aimed at quantifying the number, size distribution and evaporation of droplets produced during virtually any expiratory activity. This international research program included teams of investigators from a number of universities, with each group contributing to essential aspects of the research. This research revealed many previously unknown aspects of expiratory aerosol dynamics and characteristics. This paper will focus on the findings that the time taken for expiratory droplets to achieve short term equilibrium is comparable to that for pure water droplets and that the droplet size distributions have distinct features reflecting specific production mechanisms whose intensity varies with the nature of the activity.read more
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Characterization of expiration air jets and droplet size distributions immediately at the mouth opening
Christopher Y.H. Chao,M.P. Wan,Lidia Morawska,Graham R. Johnson,Zoran Ristovski,Megan Hargreaves,Kerrie Mengersen,Stephen Corbett,Yuguo Li,Xaiojan Xie,David Katoshevski +10 more
TL;DR: The size distributions of expiratory droplets expelled during coughing and speaking and the velocities of the expiration air jets of healthy volunteers were measured using the interferometric Mie imaging and particle image velocimetry techniques to avoid air sampling losses.
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The role of particle size in aerosolised pathogen transmission: A review
TL;DR: Expelled particles carrying pathogens do not exclusively disperse by airborne or droplet transmission but avail of both methods simultaneously and current dichotomous infection control precautions should be updated to include measures to contain both modes of aerosolised transmission.
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Review: The Use of Real-Time Fluorescence Instrumentation to Monitor Ambient Primary Biological Aerosol Particles (PBAP)
TL;DR: Real-time fluorescence monitors have been widely used in the analysis of primary biological aerosol particles (PBAP) as mentioned in this paper, which can be composed of both whole living units such as pollen, bacteria, and fungi, as well as from mechanically formed particles, such as plant debris.
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Respiratory virus RNA is detectable in airborne and droplet particles
TL;DR: It is demonstrated that individuals with symptomatic respiratory viral infections produce both large and small particles carrying viral RNA on coughing and breathing.
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Distribution of respiratory droplets in enclosed environments under different air distribution methods
TL;DR: In this paper, the spatial concentration distribution and temporal evolution of exhaled and sneezed/coughed droplets within the range of 1.0 − 10.0μm in an office room with three air distribution methods, specifically mixing ventilation (MV), displacement ventilation (DV), and under-floor air distribution (UFAD).
References
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Toward Understanding the Risk of Secondary Airborne Infection: Emission of Respirable Pathogens
TL;DR: Patients termed “superspreaders” or “dangerous disseminators” are those infrequently encountered persons with high values of cough and/or sneeze frequency, elevated pathogen concentration in respiratory fluid, and/ or increased respirable aerosol volume per expiratory event such that their pathogen emission rate is much higher than average.
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The size distribution of droplets in the exhaled breath of healthy human subjects.
TL;DR: C coughing produced the largest droplet concentrations and nose breathing the least, although considerable intersubject variability was observed, and the existence of larger sized droplets in the exhaled breath was confirmed.
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Thermal mapping of the airways in humans
E. R. McFadden,Bohdan M. Pichurko,H. F. Bowman,Edward P. Ingenito,S. Burns,N. Dowling,Julian Solway +6 more
TL;DR: Data demonstrate that in the course of conditioning inspired air the intrathoracic and intrapulmonic airways undergo profound thermal changes that extend well into the periphery of the lung.
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Dilution of Respiratory Solutes in Exhaled Condensates
Richard M. Effros,Kelly Wahlen Hoagland,Mark Bosbous,Daniel Castillo,Bradley Foss,Marshall Dunning,Meir Gare,Wen Lin,Feng Sun +8 more
TL;DR: Large variations in [Na(+)](cond) correlated well with variations of K+ in condensate ([K+](cond)) and Cl-) in condenate ([Cl-](cond)), and were attributed to differences in respiratory droplet dilution.
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Transmission of viral respiratory infections in the home.
TL;DR: Despite many years of study, the precise routes rhinovirus takes to inflict the misery of the common cold on a susceptible population remain controversial.