Quantitative Microbial Risk Assessment for Airborne Transmission of SARS-CoV-2 Via Breathing, Speaking, Singing, Coughing, and Sneezing
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Abstract
Background: Evidence for indoor airborne transmission of SARS-CoV-2 is accumulating. Objectives: We assessed of the risk of illness due to airborne SARS-CoV-2 particles from breathing, speaking, singing, coughing, and sneezing in indoor environments. Methods: A risk assessment model, AirCoV2, for exposure to SARS-CoV-2 particles in aerosol droplets was developed. Previously published data on droplets expelled by breathing, speaking, singing, coughing, and sneezing by an infected person were used as inputs. Scenarios encompassed virus concentration, exposure time, and ventilation. Newly collected data of virus RNA copies in mucus from patients are presented. Results: The expelled volume of aerosols was highest for a sneeze, followed by a cough, singing, speaking, and breathing. After 20 min of exposure, at 107 RNA copies/mL in mucus, all mean illness risks were largely estimated to be below 0.001, except for the “high” sneeze scenario. At virus concentrations above 108 RNA copies/mL, and after 2 h of exposure, in the high and “low” sneeze scenarios, the high cough scenario and the singing scenario, risks exceeded 0.01 and may become very high, whereas the low coughing scenario, the high and low speaking scenarios and the breathing scenario remained below 0.1. After 2 h of exposure, singing became the second highest risk scenario. One air exchange per hour reduced risk of illness by about a factor of 2. Six air exchanges per hour reduced risks of illness by a factor of 8–13 for the sneeze and cough scenarios and by a factor of 4–9 for the other scenarios. Discussion: The large variation in the volume of expelled aerosols is discussed. The model calculations indicated that SARS-CoV-2 transmission via aerosols outside of the 1.5-m social distancing norm can occur. Virus concentrations in aerosols and/or the amount of expelled aerosol droplets need to be high for substantial transmission via this route. AirCoV2 is made available as interactive computational tool. https://doi.org/10.1289/EHP7886
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Field data show higher SARS-CoV-2 and influenza RNA counts in finer fractions.
“Field data instead show higher SARS- CoV-2 and influenza RNA counts in finer fractions [47,58]”
From Comparative Mask Protection against Inhaling Wildfire Smoke, Allergenic Bioaerosols, and Infectious Particles (2022) · cites this paper as [47]
The Discussion (page not provided) reports SARS-CoV-2 RNA in fine airborne particles, but it does not establish consistently higher counts in finer fractions: one study found about half the RNA in 1–4 μm droplets and half in larger particles, while another found the highest concentrations in both fine and larger size ranges. The Introduction and Methods mention influenza, but do not report influenza RNA counts by particle-size fraction. (LLM, conf=0.87)
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References 82 · Cited by 142
Research works printed but not linked: 1
- WHO (World Health Organization). 2014. Infection Prevention and Control of Epidemic- and Pandemic-Prone Acute Respiratory Infections in Health Care. Geneva, Switzerland: World Health Organization. 24983124
- Authors
- Schijven, J., Vermeulen, L. C., Swart, A., Meijer, A., Duizer, E., & de Roda Husman, A. M.
- Affiliations
- Utrecht University (NL)
- National Institute for Public Health and the Environment (NL)
- Centre for Infectious Disease Control, National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
- Corresponding author
- Schijven, Jack
- Venue
- Environmental Health Perspectives
- Publisher
- American Chemical Society (ACS)
- Published
- 2021-04
- Volume
- 129
- Issue
- 4
- Pages
- 47002-47002
- ISSN
- 0091-6765 (ISSN-L)
- 1552-9924
- PMC
- PMC8016178
- OpenAlex
- W3146617261
- Cited by
- 142
- References
- 82
- Citations by year
- 2026: 8 · 2025: 15 · 2024: 17 · 2023: 28 · 2022: 37 · 2021: 34 · 2020: 3
- FWCI
- 18.75
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Licence
- public-domain
- Locations
- Environmental Health Perspectives (publishedVersion, public-domain)
- medRxiv (acceptedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion)
- PubMed (publishedVersion)
- Utrecht University Repository (Utrecht University) (submittedVersion, other-oa)
- Rivm (National Institute for Public Health and the Environment) (submittedVersion)
- Rivm (National Institute for Public Health and the Environment) (submittedVersion, other-oa)
- Funders
- Rijksinstituut voor Volksgezondheid en Milieu
- Topics
- Health Sciences › Medicine › Pulmonary and Respiratory Medicine › Infection Control and Ventilation
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Physical Sciences › Environmental Science › Health, Toxicology and Mutagenesis › Indoor Air Quality and Microbial Exposure
- Keywords
- SARS-CoV-2, airborne transmission, aerosol droplets, indoor air quality, disease risk, sneezing, cough, singing, speaking, breathing, ventilation, air exchange rate, social distancing, COVID-19 pandemic
- MeSH terms
- COVID-19, SARS-CoV-2, Aerosols, Air Microbiology, Cough, Humans, Sneezing, Disease Transmission, Infectious, Risk Assessment, Pandemics, Singing
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