Modelling aerosol transport and virus exposure with numerical simulations in relation to SARS-CoV-2 transmission by inhalation indoors

Ville Vuorinen (Corresponding Author), Mia Aarnio, Mikko Alava, Ville Alopaeus, Nina Atanasova, Mikko Auvinen, Nallannan Balasubramanian, Hadi Bordbar, Panu Erästö, Rafael Grande, Nick Hayward, Antti Hellsten, Simo Hostikka, Jyrki Hokkanen, Ossi Kaario, Aku Karvinen, Ilkka Kivistö, Marko Korhonen, Risto Kosonen, Janne KuuselaSami Lestinen, Erkki Laurila, Heikki J. Nieminen, Petteri Peltonen, Juho Pokki, Antti Puisto, Peter Råback, Henri Salmenjoki, Tarja Sironen, Monika Österberg

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1 Citation (Scopus)

Abstract

We provide research findings on the physics of aerosol and droplet dispersion relevant to the hypothesized aerosol transmission of SARS-CoV-2 during the current pandemic. We utilize physics-based modeling at different levels of complexity, along with previous literature on coronaviruses, to investigate the possibility of airborne transmission. The previous literature, our 0D-3D simulations by various physics-based models, and theoretical calculations, indicate that the typical size range of speech and cough originated droplets (d⩽20μm) allows lingering in the air for O(1h) so that they could be inhaled. Consistent with the previous literature, numerical evidence on the rapid drying process of even large droplets, up to sizes O(100μm), into droplet nuclei/aerosols is provided. Based on the literature and the public media sources, we provide evidence that the individuals, who have been tested positive on COVID-19, could have been exposed to aerosols/droplet nuclei by inhaling them in significant numbers e.g. O(100). By 3D scale-resolving computational fluid dynamics (CFD) simulations, we give various examples on the transport and dilution of aerosols (d⩽20μm) over distances O(10m) in generic environments. We study susceptible and infected individuals in generic public places by Monte-Carlo modelling. The developed model takes into account the locally varying aerosol concentration levels which the susceptible accumulate via inhalation. The introduced concept, ’exposure time’ to virus containing aerosols is proposed to complement the traditional ’safety distance’ thinking. We show that the exposure time to inhale O(100) aerosols could range from O(1s) to O(1min) or even to O(1h) depending on the situation. The Monte-Carlo simulations, along with the theory, provide clear quantitative insight to the exposure time in different public indoor environments.

Original languageEnglish
Article number104866
JournalSafety Science
Volume130
DOIs
Publication statusE-pub ahead of print - 11 Jun 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • Aerosol
  • Airborne transmission
  • CFD
  • coughing
  • COVID-19
  • Droplet
  • Large-Eddy Simulation
  • Monte-Carlo
  • SARS-CoV-2
  • Virus

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    Vuorinen, V., Aarnio, M., Alava, M., Alopaeus, V., Atanasova, N., Auvinen, M., Balasubramanian, N., Bordbar, H., Erästö, P., Grande, R., Hayward, N., Hellsten, A., Hostikka, S., Hokkanen, J., Kaario, O., Karvinen, A., Kivistö, I., Korhonen, M., Kosonen, R., ... Österberg, M. (2020). Modelling aerosol transport and virus exposure with numerical simulations in relation to SARS-CoV-2 transmission by inhalation indoors. Safety Science, 130, [104866]. https://doi.org/10.1016/j.ssci.2020.104866