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A Wells-Riley based COVID-19 infectious risk assessment model combining both short range and room scale effects

  • Research Article
  • Indoor/Outdoor Airflow and Air Quality
  • Published:
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Abstract

There is growing evidence of the high transmission potential of COVID-19 through virus-laden aerosols. Because aerosols are inhaled in various concentrations, an overall assessment of transmission risks at different indoor scales is crucial. However, a comprehensive risk assessment method that evaluates the direct link between short-range and room-scale zones is still lacking. In this paper, a risk assessment model combining both short-range and room-scale effects is developed to obtain effective reproduction number in confined indoor environments, called Turbulent Jet Wells Riley (TJWR) model. Combined with the viral load data and aerosol generation data of different human respiratory activities, the Monte Carlo simulation method is applied to calculate the quanta emission rate, which further provides the input parameters of the TJWR model. Three known outbreaks (Hangzhou banquet hall X, Guangzhou restaurant Y, and Hong Kong restaurant Z, China) are chosen to validate the TJWR model. Results show that the TJWR model is more efficient than the original Wells-Riley model. The average relative error of the TJWR model ranges between 9% and 44%, while for the Wells-Riley model, it ranges between 57% and 78%. The TJWR model also proves that infection risk assessments using the well-mixed assumption can systematically underestimate the transmission risk for those close to the source. Additionally, there is a significant positive linear correlation between the total number of exposed individuals at the short-range and the effective reproduction number. This newly developed TJWR model has great potential for rapid and real-time overall airborne transmission risk assessment in buildings and cities.

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Data availability

The data that support the findings of this study are available within the article.

Abbreviations

ACH:

air change rate per hour (h−1)

BRi :

exhalation rate of an index case (m3 h−1)

BRs :

inhalation rate of susceptible individuals (m3 h−1)

C :

quanta concentrations inhaled by susceptible individuals (quanta m−3)

C o :

quanta concentration released by the index case (quanta m−3)

Cr:

background quanta concentration (quanta m−3)

c v :

viral load (copies mL−1)

c i :

conversion factor (quanta copies−1)

ERq :

quanta emission rate (quanta h−1)

f :

transmission enhancement coefficient

IR:

individual’s infection risk (%)

k :

deposition rate (h−1)

N :

number of susceptible individuals

P :

individual’s infection probability (%)

\({P_{{\rm{E}}{{\rm{R}}_{\rm{q}}}}}\) :

probability of occurrence of each ERq

R :

effective reproduction number

R o :

basic reproduction number

R act :

event reproduction number

RE:

relative error (%)

\(\overline S \) :

average dilution ratio

TILc :

combined total inward leakage rate (%)

TOLc :

combined total outward leakage rate (%)

V :

volume of a shared indoors (m3)

V jd :

droplet volume concentration (mL m−3)

ω :

short-range scale (≤2 m)

ω 1 :

short-range scale (0–1 m)

ω 2 :

short-range scale (1–2 m)

ψ :

room-scale (>2 m)

γ :

fraction of infectious aerosols (%)

λ :

virus inactivation rate (h−1)

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Acknowledgements

We acknowledge the funding support from National Key R&D Program of China (2018YFE0106100), the Fundamental Research Funds for the Central Universities (K20220163).

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Authors and Affiliations

  1. College of Civil Engineering and Architecture, Zhejiang University, Hangzhou, China

    Yinshuai Feng, Yifan Fan, Xiaoyu Luo & Jian Ge

  2. Center for Balance Architecture, Zhejiang University, Hangzhou, China

    Yinshuai Feng & Yifan Fan

  3. International Research Center for Green Building and Low-Carbon City, International Campus, Zhejiang University, Haining, China

    Yinshuai Feng, Yifan Fan, Xiaoyu Luo & Jian Ge

Authors
  1. Yinshuai Feng
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  2. Yifan Fan
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  3. Xiaoyu Luo
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Contributions

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Yinshuai Feng, Yifan Fan, Xiaoyu Luo and Jian Ge. The first draft of the manuscript was written by Yinshuai Feng and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Yifan Fan.

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Feng, Y., Fan, Y., Luo, X. et al. A Wells-Riley based COVID-19 infectious risk assessment model combining both short range and room scale effects. Build. Simul. 17, 93–111 (2024). https://doi.org/10.1007/s12273-023-1060-y

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  • DOI: https://doi.org/10.1007/s12273-023-1060-y

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