Simulation of vertical concentration gradient of influenza viruses in dust resuspended by walking
Particles are resuspended from the floor by walking and are subject to turbulent transport in the human aerodynamic wake. These processes may generate a vertical concentration gradient of particles. To estimate the magnitude of turbulence generated by walking, we measured the velocity field in the w...
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Published in | Indoor air Vol. 25; no. 4; pp. 428 - 440 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
England
Blackwell Publishing Ltd
01.08.2015
Hindawi Limited |
Subjects | |
Online Access | Get full text |
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Summary: | Particles are resuspended from the floor by walking and are subject to turbulent transport in the human aerodynamic wake. These processes may generate a vertical concentration gradient of particles. To estimate the magnitude of turbulence generated by walking, we measured the velocity field in the wake from floor to ceiling at 10‐cm intervals with a sonic anemometer. The resulting eddy diffusion coefficients varied between 0.06 and 0.20 m2/s and were maximal at ~0.75–1 m above the floor, approximately the height of the swinging hand. We applied the eddy diffusion coefficients in an atmospheric transport model to predict concentrations of resuspended influenza virus as a function of the carrier particle size, height in the room, and relative humidity, which affects the resuspension rate coefficient and virus viability. Results indicated that the concentration of resuspended viruses at 1 m above the floor was up to 40% higher than at 2 m, depending on particle size. For exposure to total resuspended viruses, the difference at 1 vs. 2 m was 11–14%. It is possible that shorter people are exposed to higher concentrations of resuspended dust, including pathogens, although experimental evidence is needed to verify this proposition. |
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Bibliography: | Figure S1. The numerical grid space used for simulation of concentrations. The grid is divided into 128 nodes in the vertical direction and traverses through iterations along the horizontal direction until the concentration at each node reaches its steady-state value. Figure S2. Vertical velocity autocorrelations at three heights for (a) one person walking, (b) two persons walking, and (c) three persons walking. Figure S3. Number of particles in the floor dust per unit area at (a) 15% RH, (b) 35% RH, (c) 55% RH, (d) 75% RH, and (e) 95% RH. Figure S4. Hypothesized eddy diffusion coefficient profile for a single 1-m tall child walking in the room. Figure S5. Concentration of infectious viruses as a function of height, normalized to the concentration at ground level at (a) 15% RH and (b) 95% RH, resulting from one 1-m tall child walking in the room. ark:/67375/WNG-7N2L5TXT-D istex:89730E8CCBA3F0B1ABDE169F47A41B18D0D116C5 Virginia Tech's Institute for Critical Technology and Applied Science ArticleID:INA12156 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0905-6947 1600-0668 |
DOI: | 10.1111/ina.12156 |