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A study of fluid dynamics and human physiology factors driving droplet dispersion from a human sneeze
Recent studies have indicated that COVID-19 is an airborne disease, which has driven conservative social distancing and widescale usage of face coverings. Airborne virus transmission occurs through droplets formed during respiratory events (breathing, speaking, coughing, and sneezing) associated wit...
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| Published in: | Physics of fluids (1994) 2020-11, Vol.32 (11), p.111904-111904 |
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| Main Authors: | , , , |
| Format: | Article |
| Language: | English |
| Citations: | Items that this one cites Items that cite this one |
| Online Access: | Get full text |
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| Summary: | Recent studies have indicated that COVID-19 is an airborne disease, which has driven
conservative social distancing and widescale usage of face coverings. Airborne virus
transmission occurs through droplets formed during respiratory events (breathing,
speaking, coughing, and sneezing) associated with the airflow through a network of nasal
and buccal passages. The airflow interacts with saliva/mucus films where droplets are
formed and dispersed, creating a route to transmit SARS-CoV-2. Here, we present a series
of numerical simulations to investigate droplet dispersion from a sneeze while varying a
series of human physiological factors that can be associated with illness, anatomy, stress
condition, and sex of an individual. The model measures the transmission risk utilizing an
approximated upper respiratory tract geometry for the following variations: (1) the effect
of saliva properties and (2) the effect of geometric features within the buccal/nasal
passages. These effects relate to natural human physiological responses to illness,
stress, and sex of the host as well as features relating to poor dental health. The
results find that the resulting exposure levels are highly dependent on the fluid dynamics
that can vary depending on several human factors. For example, a sneeze without flow in
the nasal passage (consistent with congestion) yields a 300% rise in the droplet content
at 1.83 m (≈6 ft) and an increase over 60% on the spray distance 5 s after the sneeze.
Alternatively, when the viscosity of the saliva is increased (consistent with the human
response to illness), the number of droplets is both fewer and larger, which leads to an
estimated 47% reduction in the transmission risk. These findings yield novel insight into
variability in the exposure distance and indicate how physiological factors affect
transmissibility rates. Such factors may partly relate to how the immune system of a human
has evolved to prevent transmission or be an underlying factor driving superspreading
events in the COVID-19 pandemic. |
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| ISSN: | 1070-6631 1089-7666 |
| DOI: | 10.1063/5.0032006 |