TY - JOUR
T1 - Quantifying the effect of a mask on expiratory flows
AU - Bourrianne, Philippe
AU - Xue, Nan
AU - Nunes, Janine
AU - Abkarian, Manouk
AU - Stone, Howard A.
N1 - Funding Information:
The authors acknowledge the Princeton Open Ventilation Monitor Collaboration for the development of the flow meter and pressure sensor used in the study. We thank Michael Roselli and Tim McDowd from FLIR for the gracious loan of the infrared camera. We thank the NSF for support via the RAPID grant CBET 2029370 and grant CBET 2116184, as well as the support of the ANR via the RA COVID grant ANR-21-CO15-0004. The study was approved by the Princeton University Institutional Review Board (protocol no. 12834).
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/11
Y1 - 2021/11
N2 - Face masks are used widely to mitigate the spread of infectious diseases. While their main purpose is to filter pathogenic droplets, masks also represent a porous barrier to exhaled and inhaled air flow. In this study, we characterize the aerodynamic effect of the presence of a mask by tracking the air exhaled by a person through a mask, using both infrared imaging and particle image velocimetry performed on illuminated fog droplets surrounding a subject. We show how a mask confines the exhaled flows within tens of centimeters in front of a person breathing or speaking. In addition, we show that the tissue of common surgical face masks has a low permeability, which efficiently transforms the jetlike flows of exhalation produced during breathing or speaking into quasivertical buoyancy-driven flows. Therefore, wearing a mask offers a strong mitigation of direct transport of infectious material in addition to providing a filtering function. By comparing results on human subjects and model experiments, we propose a model to rationalize how a mask changes the air flow, and thus we provide quantitative insights that are useful for descriptions of disease transmission.
AB - Face masks are used widely to mitigate the spread of infectious diseases. While their main purpose is to filter pathogenic droplets, masks also represent a porous barrier to exhaled and inhaled air flow. In this study, we characterize the aerodynamic effect of the presence of a mask by tracking the air exhaled by a person through a mask, using both infrared imaging and particle image velocimetry performed on illuminated fog droplets surrounding a subject. We show how a mask confines the exhaled flows within tens of centimeters in front of a person breathing or speaking. In addition, we show that the tissue of common surgical face masks has a low permeability, which efficiently transforms the jetlike flows of exhalation produced during breathing or speaking into quasivertical buoyancy-driven flows. Therefore, wearing a mask offers a strong mitigation of direct transport of infectious material in addition to providing a filtering function. By comparing results on human subjects and model experiments, we propose a model to rationalize how a mask changes the air flow, and thus we provide quantitative insights that are useful for descriptions of disease transmission.
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U2 - 10.1103/PhysRevFluids.6.110511
DO - 10.1103/PhysRevFluids.6.110511
M3 - Article
AN - SCOPUS:85120534455
SN - 2469-990X
VL - 6
JO - Physical Review Fluids
JF - Physical Review Fluids
IS - 11
M1 - 110511
ER -