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. 2022 Dec 23;16(5):765–780. doi: 10.1007/s12273-022-0968-y

Predominance of inhalation route in short-range transmission of respiratory viruses: Investigation based on computational fluid dynamics

Wenzhao Chen 1, Li Liu 2, Jian Hang 3, Yuguo Li 1,4,✉
PMCID: PMC9782262  PMID: 36575690

Abstract

During the Coronavirus disease 2019 pandemic, short-range virus transmission has been observed to have a higher risk of causing infection than long-range virus transmission. However, the roles played by the inhalation and large droplet routes cannot be distinguished in practice. A recent analytical study revealed the predominance of short-range inhalation over the large droplet spray route as causes of respiratory infections. In the current study, short-range exposure was analyzed via computational fluid dynamics (CFD) simulations using a discrete phase model. Detailed facial membranes, including eyes, nostrils, and a mouth, were considered. In CFD simulations, there is no need for a spherical approximation of the human head for estimating deposition nor the “anisokinetic aerosol sampling” approximation for estimating inhalation in the analytical model. We considered two scenarios (with two spheres [Scenario 1] and two human manikins [Scenario 2]), source-target distances of 0.2 to 2 m, and droplet diameters of 3 to 1,500 µm. The overall CFD exposure results agree well with data previously obtained from a simple analytical model. The CFD results confirm the predominance of the short-range inhalation route beyond 0.2 m for expiratory droplets smaller than 50 µm during talking and coughing. A critical droplet size of 87.5 µm was found to differentiate droplet behaviors. The number of droplets deposited on the target head exceeded those exposed to facial membranes, which implies a risk of exposure through the immediate surface route over a short range.

Electronic Supplementary Material (ESM)

the Supplementary Materials are available in the online version of this article at 10.1007/s12273-022-0968-y.

Keywords: airborne transmission, close contact, short-range inhalation, large droplet spray, computational fluid dynamics

Electronic Supplementary Material

12273_2022_968_MOESM1_ESM.pdf (1MB, pdf)

Predominance of inhalation route in short-range transmission of respiratory viruses: Investigation based on computational fluid dynamics

Acknowledgements

This work was supported by a General Research Fund (grant number 17202719) provided by the Research Grants Council of Hong Kong.

Footnotes

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could appear to influence the work reported in this paper.

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Supplementary Materials

12273_2022_968_MOESM1_ESM.pdf (1MB, pdf)

Predominance of inhalation route in short-range transmission of respiratory viruses: Investigation based on computational fluid dynamics

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