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Research Article
Tomoaki Yoshida
Fujita Health University
Corresponding Author
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In the pandemic of COVID-19, a rigorous lockdown or social distancing will mitigate transmission, but some alternative strategy is needed especially for mass-gathering events. Given that the main path of transmission is through droplets or aerosols, a swift removal of them immediately after exhalation, which may attain “personal air zoning”, would be more effective and feasible than whole room ventilations. In the present study, an artificial fog was employed as a model aerosol to be exhaled and readily visualized on movies and quantified on dust indicators. The temporal and spatial distribution of this model microdroplet amounts corresponded reasonably well with previously published data, where talking air flow was quantified as a negative staining, in that it predominates below the mouth height rather than horizontal, and that it travels forward over 1.5 m in 30 sec. Under this model condition, nearly 99% of exhaled microdroplets could be efficiently blown up beyond the bystanders’ head heights, when a minimal air flow (2.5 m/s) was applied, using a typical personal cooling fan just below the chin. This swift upward removal of microdroplets would prevent bystanders’ immediate inhalation and provide sufficient probation periods for safe exhaustion from indoor spaces.
Keywords
SARS-cov2, aerosol transmission, intervention, zoning, ventilation
Figure 1
Figure 2
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Figure 4
No competing interests reported.
This is a list of supplementary files associated with this preprint. Click to download.
- YoshidasuplFeb11.pptx
Supplementary Fig. S1 Microscopic view of microdroplets used The artificial fog employed was sedimented to a plastic dish and observed under a phase contrast microscope at X400. The size scale was obtained on a standard micrometer for objective lenses. Supplementary Fig. S2 Still pictures of smoke videos without devices Still pictures of innate exhalations by the corresponding author were snapshotted to compare the behaviors of exhaled air. The capitalized phonem was pronounced at the shots. Supplementary Fig. S3 Still pictures of smoke videos with safety devices Still pictures of smoke videos using mouth shield or neck fan were snapshotted, when the capitalized phonem was pronounced. Supplementary video The corresponding author himself has inhaled the artificial fog and spoke “Stay Healthy” several times with or without mouth shield or the neck fan.
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A new preprint design is coming!
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research Article
Tomoaki Yoshida
Fujita Health University
Corresponding Author
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 15 Mar, 2021
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
License:
This work is licensed under a CC BY 4.0 License. Read Full License
In the pandemic of COVID-19, a rigorous lockdown or social distancing will mitigate transmission, but some alternative strategy is needed especially for mass-gathering events. Given that the main path of transmission is through droplets or aerosols, a swift removal of them immediately after exhalation, which may attain “personal air zoning”, would be more effective and feasible than whole room ventilations. In the present study, an artificial fog was employed as a model aerosol to be exhaled and readily visualized on movies and quantified on dust indicators. The temporal and spatial distribution of this model microdroplet amounts corresponded reasonably well with previously published data, where talking air flow was quantified as a negative staining, in that it predominates below the mouth height rather than horizontal, and that it travels forward over 1.5 m in 30 sec. Under this model condition, nearly 99% of exhaled microdroplets could be efficiently blown up beyond the bystanders’ head heights, when a minimal air flow (2.5 m/s) was applied, using a typical personal cooling fan just below the chin. This swift upward removal of microdroplets would prevent bystanders’ immediate inhalation and provide sufficient probation periods for safe exhaustion from indoor spaces.
Figure 1
Figure 2
Figure 3
Figure 4
No competing interests reported.
This is a list of supplementary files associated with this preprint. Click to download.
- YoshidasuplFeb11.pptx
Supplementary Fig. S1 Microscopic view of microdroplets used The artificial fog employed was sedimented to a plastic dish and observed under a phase contrast microscope at X400. The size scale was obtained on a standard micrometer for objective lenses. Supplementary Fig. S2 Still pictures of smoke videos without devices Still pictures of innate exhalations by the corresponding author were snapshotted to compare the behaviors of exhaled air. The capitalized phonem was pronounced at the shots. Supplementary Fig. S3 Still pictures of smoke videos with safety devices Still pictures of smoke videos using mouth shield or neck fan were snapshotted, when the capitalized phonem was pronounced. Supplementary video The corresponding author himself has inhaled the artificial fog and spoke “Stay Healthy” several times with or without mouth shield or the neck fan.
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