For transmission by smaller aerosol particles, see Airborne transmission.
Some infectious diseases can be spread via respiratory droplets expelled from the mouth and nose, as when a person sneezes.
A respiratory droplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract surfaces. Respiratory droplets are produced naturally as a result of breathing, speaking, sneezing, coughing, or vomiting, so they are always present in our breath, but speaking and coughing increase their number.[1][2][3]
Droplet sizes range from < 1 μm to 1000 μm,[1][2] and in typical breath there are around 100 droplets per litre of breath. So for a breathing rate of 10 litres per minute this means roughly 1000 droplets per minute, the vast majority of which are a few micrometres across or smaller.[1][2] As these droplets are suspended in air, they are all by definition aerosols. However, large droplets (larger than about 100 μm, but depending on conditions) rapidly fall to the ground or another surface and so are only briefly suspended, while droplets much smaller than 100 μm (which is most of them) fall only slowly and so form aerosols with lifetimes of minutes or more, or at intermediate size, may initially travel like aerosols but at a distance fall to the ground like droplets ("jet riders").[4]
These droplets can contain infectious bacterial cells or virus particles they are important factors in the transmission of respiratory diseases. In some cases, in the study of disease transmission a distinction between what are called "respiratory droplets" and what are called "aerosols" is made, with only larger droplets referred to as "respiratory droplets" and smaller ones referred to as "aerosols" but this arbitrary distinction has never been supported experimentally or theoretically,[5][3] and is not consistent with the standard definition of an aerosol.
^ abcJohnson, G.R.; Morawska, L.; Ristovski, Z.D.; Hargreaves, M.; Mengersen, K.; Chao, C.Y.H.; Wan, M.P.; Li, Y.; Xie, X.; Katoshevski, D.; Corbett, S. (2011-12-01). "Modality of human expired aerosol size distributions". Journal of Aerosol Science. 42 (12): 839–851. Bibcode:2011JAerS..42..839J. doi:10.1016/j.jaerosci.2011.07.009. ISSN 0021-8502.
^ abcGregson, Florence K. A.; Watson, Natalie A.; Orton, Christopher M.; Haddrell, Allen E.; McCarthy, Lauren P.; Finnie, Thomas J. R.; Gent, Nick; Donaldson, Gavin. C.; Shah, Pallav L.; Calder, James D.; Bzdek, Bryan R. (2021-02-26). "Comparing aerosol concentrations and particle size distributions generated by singing, speaking and breathing". Aerosol Science and Technology. 55 (6): 681–691. Bibcode:2021AerST..55..681G. doi:10.1080/02786826.2021.1883544. hdl:10044/1/87506. ISSN 0278-6826. S2CID 233353106.
^ abBourouiba, Lydia (2021-01-05). "The Fluid Dynamics of Disease Transmission". Annual Review of Fluid Mechanics. 53 (1): 473–508. Bibcode:2021AnRFM..53..473B. doi:10.1146/annurev-fluid-060220-113712. ISSN 0066-4189. S2CID 225114407.
^Hunziker, Patrick (2021-10-01). "Minimising exposure to respiratory droplets, 'jet riders' and aerosols in air-conditioned hospital rooms by a 'Shield-and-Sink' strategy". BMJ Open. 11 (10): e047772. doi:10.1136/bmjopen-2020-047772. ISSN 2044-6055. PMC 8520596. PMID 34642190.
A respiratorydroplet is a small aqueous droplet produced by exhalation, consisting of saliva or mucus and other matter derived from respiratory tract...
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Droplet nuclei are aerosols formed from the evaporation of respiratorydroplets. They are generally smaller than 5 μm in diameter. Droplet nuclei are formed...
way of respiratorydroplets, generated by coughing, sneezing, or talking. Respiratorydroplet transmission is the usual route for respiratory infections...
membranes with respiratorydroplets or fomites. As with all respiratory pathogens once presumed to transmit via respiratorydroplets, it is highly likely...
other infections that occurs in the lower respiratory tract. You can contract this infection from airborne droplets, and if inhaled you are at risk of this...
An aerosol is a suspension of fine solid particles or liquid droplets in air or another gas. Aerosols can be generated from natural or human causes. The...
around 80–120 nm. Rhinoviruses are transmitted through aerosols, respiratorydroplets, fomites, and direct person-to-person contact. They primarily infect...
spread by respiratorydroplets from an infected person, spread by talking, coughing or sneezing, or by touching something that has droplets on it and...
In humans, influenza viruses are primarily transmitted through respiratorydroplets from coughing and sneezing. Transmission through aerosols and surfaces...
Mathematical Models to Assess Responses to an Outbreak of an Emerged Viral Respiratory Disease. National Centre for Epidemiology and Population Health. ISBN 1-74186-357-0...
distinction is no longer used. Respiratorydroplets were thought to rapidly fall to the ground after emission: but smaller droplets and aerosols also contain...
respiratorydroplets derived from saliva and/or respiratory mucus, with sizes ranging from about 1 μm to 2 mm. Wells' insight was that such droplets would...
main energy source used by human cells, many pathogens including the respiratory pathogen Haemophilus influenzae specialise in using other carbon sources...
from camels, either during direct contact or indirectly through respiratorydroplets. Spread between humans typically requires close contact with an infected...
Transmission of pathogens via respiratorydroplets This disambiguation page lists articles associated with the title Respiratory route. If an internal link...
transmission by fomites has been considered inefficient compared with respiratorydroplet transmission. Burke, James P. (May 2009). Pioneers of Second Fork...
glass screen designed to protect food or people from the exposure to respiratorydroplets, which are dispensed when coughing, sneezing, or speaking. Sneeze...
person-to-person contact via respiratorydroplets and by auto inoculation in persons carrying the bacteria in their upper respiratory tracts. It can be a cause...
infections in up to 25% of cases. Mycoplasma pneumoniae is spread through respiratorydroplet transmission.[citation needed] Once attached to the mucosa of a host...
include respiratorydroplets, blood, or mother to fetus. As with all respiratory pathogens once presumed to transmit via respiratorydroplets, it is highly...
aerosolized contaminants between the wearer and nearby people via respiratorydroplets ejected when sneezing, coughing, forceful expiration or unintentionally...
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