Analytic modeling and risk assessment of aerial transmission of SARS-CoV-2 virus through vaping expirations in shared micro-environments

Background. E-cigarettes are an important harm reduction tool that provides smokers an alternative for nicotine consumption that is much safer than smoking. It is important to asses its safety under preventive and containment measures undertaken during the COVID-19 pandemic.Methods. We develop a theoretical risk model to assess the contagion risk by aerial trans mission of the SARS-CoV-2 virus carried by e–cigarette aerosol (ECA) in shared indoor spaces, a home and restaurant scenarios, with natural and mechanical ventilation, with and without face masks. We also provide the theoretical elements to explain the visibility of exhaled ECA, which has important safety implications.Results. In a home or restaurant scenarios bystanders exposed to ECA expirations by an infectious vaper (and not wearing face masks) face a 1% increase of risk of contagion with respect to a “control case” scenario defined by exclusively rest breathing without vaping. This relative added risk becomes 5 - 17% for high intensity vaping, 44 - 176% and over 260% for speaking for various periods or coughing (all without vaping). Mechanical ventilation significantly decrease infective emissions but keep the same proportionality in risk percentages. Face masks of common usage effectively protect wearers from respiratory droplets and droplet nuclei possibly emitted by mask-less vapers as long as they avoid direct exposure to the visible exhaled vaping jet.Conclusions. Vaping emissions in shared indoor spaces involve only a minuscule added risk of COVID-19 contagion with respect to the already existing (unavoidable) risk from continuous breathing, significantly less than speaking or coughing. Protection of bystanders from this contagion does not require extra preventive measures besides those already recommended (1.5 meters separation and wearing face masks).

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Analytic modeling and risk assessment of aerial transmission of SARS-CoV-2 virus through vaping expirations in shared micro-environments

10.21203/rs.3.rs-340115/v1 ◽

2021 ◽

Author(s):

Roberto Sussman ◽

Eliana Golberstein ◽

Riccardo Polosa

Keyword(s):

Mechanical Ventilation ◽

Risk Model ◽

Case Scenario ◽

Direct Exposure ◽

Containment Measures ◽

Nicotine Consumption ◽

Contagion Risk ◽

Droplet Nuclei ◽

Respiratory Droplets ◽

Indoor Spaces

Abstract Background. E-cigarettes are an important harm reduction tool that provides smokers an alternative for nicotine consumption that is much safer than smoking. It is important to asses its safety under preventive and containment measures undertaken during the COVID-19 pandemic. Methods. We develop a theoretical risk model to assess the contagion risk by aerial transmission of the SARS-CoV-2 virus carried by e–cigarette aerosol (ECA) in shared indoor spaces, a home and restaurant scenarios, with natural and mechanical ventilation, with and without face masks. We also provide the theoretical elements to explain the visibility of exhaled ECA, which has important safety implications. Results. In a home or restaurant scenarios bystanders exposed to ECA expirations by an infectious vaper (and not wearing face masks) face a 1% increase of risk of contagion with respect to a “control case” scenario defined by exclusively rest breathing without vaping. This relative added risk becomes 5 - 17% for high intensity vaping, 44 - 176% and over 260% for speaking for various periods or coughing (all without vaping). Mechanical ventilation significantly decrease infective emissions but keep the same proportionality in risk percentages. Face masks of common usage effectively protect wearers from respiratory droplets and droplet nuclei possibly emitted by mask-less vapers as long as they avoid direct exposure to the visible exhaled vaping jet. Conclusions. Vaping emissions in shared indoor spaces involve only a minuscule added risk of COVID-19 contagion with respect to the already existing (unavoidable) risk from continuous breathing, significantly less than speaking or coughing. Protection of bystanders from this contagion does not require extra preventive measures besides those already recommended (1.5 meters separation and wearing face masks).

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Beyond well-mixed: a simple probabilistic model of airborne disease transmission in indoor spaces

10.1101/2021.12.05.21267319 ◽

2021 ◽

Author(s):

Sijian Tan ◽

Zhihang Zhang ◽

Kevin Maki ◽

Krzysztof J. Fidkowski ◽

Jesse Capecelatro

Keyword(s):

Disease Transmission ◽

Risk Model ◽

Ventilation Rate ◽

Turbulent Dispersion ◽

Balance Model ◽

Wide Range ◽

Ventilation Rates ◽

Airborne Disease ◽

Droplet Nuclei ◽

Indoor Spaces

AbstractWe develop a simple model for assessing risk of airborne disease transmission that accounts for non-uniform mixing in indoor spaces and is compatible with existing epidemiological models. A database containing 174 high-resolution simulations of airflow in classrooms, lecture halls, and buses is generated and used to quantify the spatial distribution of expiratory droplet nuclei for a wide range of ventilation rates, exposure times, and room configurations. Imperfect mixing due to obstructions, buoyancy, and turbulent dispersion results in concentration fields with significant variance. The spatial non-uniformity is found to be accurately described by a shifted lognormal distribution. A well-mixed mass balance model is used to predict the mean, and the standard deviation is parameterized based on ventilation rate and room geometry. When employed in a dose-response function risk model, infection probability can be estimated considering spatial heterogeneity that contributes to both short- and long-range transmission.

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Aerial transmission of SARS-CoV-2 virus (and pathogens in general) through environmental e-cigarette aerosol

10.1101/2020.11.21.20235283 ◽

2020 ◽

Author(s):

Roberto A. Sussman ◽

Eliana Golberstein ◽

Riccardo Polosa

Keyword(s):

Risk Evaluation ◽

Respiratory Mechanics ◽

Laboratory Data ◽

Horizontal Distance ◽

Case Scenario ◽

Low Intensity ◽

Shared Spaces ◽

Submicron Droplets ◽

Respiratory Droplets ◽

Indoor Spaces

AbstractWe examine the plausibility, scope and risks of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets carried by exhaled e–cigarette aerosol (ECA). Observational and laboratory data suggests considering cigarette smoking and mouth breathing through a mouthpiece as convenient proxies to infer the respiratory mechanics and droplets sizes and their rate of emission that should result from vaping. To infer distances for possible direct contagion we model exhaled ECA flow as an intermittent turbulent jet evolving into an unstable puff, estimating for low intensity vaping (practiced by 80-90% of vapers) ECA expirations the emission of 2-230 respiratory submicron droplets per puff a horizontal distance spread of 1-2 meters, with intense vaping possibly carrying hundreds and up to 1000 droplets per puff in the submicron range a distance spread over 2 meters. Bystanders exposed to low intensity expirations from an infectious vaper in indoor spaces (home and restaurant scenarios) face a 1% increase of risk of indirect contagion with respect to a “control case” scenario defined by exclusively rest breathing without vaping. This relative added risk becomes 5 – 17% for high intensity vaping, 40 – 90% and over 260% for speaking or coughing (without vaping). This risk evaluation remains practically unchanged in shared spaces with universal usage of face masks. We estimate that disinfectant properties of glycols in ECA are unlikely to act efficiently on pathogens carried by vaping expirations under realistic conditions.

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Aerial Transmission of the SARS-CoV-2 Virus through Environmental E-Cigarette Aerosols: Implications for Public Policies

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18041437 ◽

2021 ◽

Vol 18 (4) ◽

pp. 1437

Author(s):

Roberto A. Sussman ◽

Eliana Golberstein ◽

Riccardo Polosa

Keyword(s):

Emission Rate ◽

Respiratory Activity ◽

Separation Distance ◽

Mitigation Strategies ◽

Relative Risks ◽

Respiratory Flow ◽

Outdoor Spaces ◽

Direct Exposure ◽

Social Separation ◽

Indoor Spaces

We discuss the implications of possible contagion of COVID-19 through e-cigarette aerosol (ECA) for prevention and mitigation strategies during the current pandemic. This is a relevant issue when millions of vapers (and smokers) must remain under indoor confinement and/or share public outdoor spaces with non-users. The fact that the respiratory flow associated with vaping is visible (as opposed to other respiratory activities) clearly delineates a safety distance of 1–2 m along the exhaled jet to prevent direct exposure. Vaping is a relatively infrequent and intermittent respiratory activity for which we infer a mean emission rate of 79.82 droplets per puff (6–200, standard deviation 74.66) comparable to mouth breathing, it adds into shared indoor spaces (home and restaurant scenarios) a 1% extra risk of indirect COVID-19 contagion with respect to a “control case” of existing unavoidable risk from continuous breathing. As a comparative reference, this added relative risk increases to 44–176% for speaking 6–24 min per hour and 260% for coughing every 2 min. Mechanical ventilation decreases absolute emission levels but keeps the same relative risks. As long as direct exposure to the visible exhaled jet is avoided, wearing of face masks effectively protects bystanders and keeps risk estimates very low. As a consequence, protection from possible COVID-19 contagion through vaping emissions does not require extra interventions besides the standard recommendations to the general population: keeping a social separation distance of 2 m and wearing of face masks.

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Coupling Computational Fluid Dynamics Simulations and Statistical Moments for Designing Healthy Indoor Spaces

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph16050800 ◽

2019 ◽

Vol 16 (5) ◽

pp. 800 ◽

Cited By ~ 1

Author(s):

Shamia Hoque ◽

Firoza Omar

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Air Flow ◽

Particle Dispersion ◽

Statistical Moments ◽

Dispersion Pattern ◽

Case Scenario ◽

Worst Case ◽

Site Specific ◽

Indoor Spaces

Cross-contamination between occupants in an indoor space may occur due to transfer of infectious aerosols. Computational fluid dynamics (CFD) provides detailed insight into particle transport in indoor spaces. However, such simulations are site-specific. This study couples CFD with statistical moments and establishes a framework that transitions site-specific results to generating guidelines for designing “healthy” indoor spaces. Eighteen cases were simulated, and three parameters were assessed: inlet/outlet location, air changes per hour, and the presence/absence of desks. Aerosol release due to a simulated “sneeze” in a two-dimensional ventilated space was applied as a test case. Mean, standard deviation, and skewness of the velocity profiles and particle locations gave an overall picture of the spread and movement of the air flow in the domain. A parameter or configuration did not dominate the values, confirming the significance of considering the combined influence of multiple parameters for determining localized air-flow characteristics. Particle clustering occurred more when the inlet was positioned above the outlet. The particle dispersion pattern could be classified into two time zones: “near time”, <60 s, and “far time”, >120 s. Based on dosage, the 18 cases were classified into three groups ranging from worst case scenario to best case scenario.

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Evaluation of Survivability of a Ship After Damage with Application of a Risk Calculation Method

10.3940/rina.ijme.2020.a1.512a ◽

2020 ◽

Vol 162 (A1) ◽

Author(s):

P S Szulczewski

Keyword(s):

Calculation Method ◽

Probabilistic Model ◽

Risk Model ◽

Limited Information ◽

Case Scenario ◽

Risk Calculation ◽

Risk Levels ◽

Valid Method ◽

Comparison Of Results ◽

Industry Standard

This paper contains calculations of risk for a selected damage case scenario. The calculations took place with use of a risk model designed for evaluating the safety of ships and were compared with the available and published industry standard (as included in SOLAS 2009) as well. The comparison of results is presented in the form of a discussion and concludes that exact risk levels can be obtained at any stage of the vessel's life. The currently valid method as included in SOLAS 2009 regulation provides limited information about the actual survivability of a vessel in emergency conditions. It is hence very difficult to compare the current probabilistic model with risk based survivability calculations to evaluate the actual safety provided by an investigated vessel should it subsequently be severely damaged.

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Sheet Barrier and Intubating Stylet

Encyclopedia ◽

10.3390/encyclopedia1040081 ◽

2021 ◽

Vol 1 (4) ◽

pp. 1058-1075

Author(s):

Phil B. Tsai ◽

Hsiang-Ning Luk

Keyword(s):

Health Care ◽

Tracheal Intubation ◽

Health Care Providers ◽

Protective Equipment ◽

Medical Procedures ◽

Care Providers ◽

Risk Of Infection ◽

Plastic Sheet ◽

Droplet Nuclei ◽

Respiratory Droplets

Coronavirus disease 2019 (COVID-19), a respiratory syndrome caused by SARS-CoV-2, can be transmitted through respiratory droplets and aerosols of droplet nuclei. Aerosol-generating medical procedures (AGMP) are needed to take care of critically ill patients but place health care providers at risk of infection. With limited supplies of personal protective equipment (PPE), barrier systems were developed to help protect health care providers during tracheal intubation. The video intubating stylet shows promise to become the preferred intubation device in conjunction with plastic sheet barriers during the COVID-19 pandemic.

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Assessing coughing-induced influenza droplet transmission and implications for infection risk control

Epidemiology and Infection ◽

10.1017/s0950268815001739 ◽

2015 ◽

Vol 144 (2) ◽

pp. 333-345 ◽

Cited By ~ 7

Author(s):

Y.-H. CHENG ◽

C.-H. WANG ◽

S.-H. YOU ◽

N.-H. HSIEH ◽

W.-Y. CHEN ◽

...

Keyword(s):

Respiratory Tract ◽

Risk Model ◽

Control Measure ◽

Influenza Infection ◽

Infection Risk ◽

Transmission Dynamics ◽

Human Respiratory Tract ◽

Host Interactions ◽

And Control ◽

Respiratory Droplets

SUMMARYIndoor transmission of respiratory droplets bearing influenza within humans poses high risks to respiratory function deterioration and death. Therefore, we aimed to develop a framework for quantifying the influenza infection risk based on the relationships between inhaled/exhaled respiratory droplets and airborne transmission dynamics in a ventilated airspace. An experiment was conducted to measure the size distribution of influenza-containing droplets produced by coughing for a better understanding of potential influenza spread. Here we integrated influenza population transmission dynamics, a human respiratory tract model, and a control measure approach to examine the indoor environment–virus–host interactions. A probabilistic risk model was implemented to assess size-specific infection risk for potentially transmissible influenza droplets indoors. Our results found that there was a 50% probability of the basic reproduction number (R0) exceeding 1 for small-size influenza droplets of 0·3–0·4 µm, implicating a potentially high indoor infection risk to humans. However, a combination of public health interventions with enhanced ventilation could substantially contain indoor influenza infection. Moreover, the present dynamic simulation and control measure assessment provide insights into why indoor transmissible influenza droplet-induced infection is occurring not only in upper lung regions but also in the lower respiratory tract, not normally considered at infection risk.

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Modeling Aerial Transmission of Pathogens (Including the SARS-CoV-2 Virus) through Aerosol Emissions from E-Cigarettes

Applied Sciences ◽

10.3390/app11146355 ◽

2021 ◽

Vol 11 (14) ◽

pp. 6355

Author(s):

Roberto A. Sussman ◽

Eliana Golberstein ◽

Riccardo Polosa

Keyword(s):

Cigarette Smoking ◽

Theoretical Modeling ◽

Horizontal Distance ◽

Axially Symmetric ◽

Low Intensity ◽

Direct Exposure ◽

Submicron Droplets ◽

Starting Jet ◽

Aerosol Emissions ◽

Respiratory Droplets

We examine the plausibility of aerial transmission of pathogens (including the SARS-CoV-2 virus) through respiratory droplets that might be carried by exhaled e-cigarette aerosol (ECA). Given the lack of empiric evidence on this phenomenon, we consider available evidence on cigarette smoking and respiratory droplet emission from mouth breathing through a mouthpiece as convenient proxies to infer the capacity of vaping to transport pathogens in respiratory droplets. Since both exhaled droplets and ECA droplets are within the Stokes regime, the ECA flow acts effectively as a visual tracer of the expiratory flow. To infer quantitatively the direct exposure distance, we consider a model that approximates exhaled ECA flow as an axially symmetric intermittent steady starting jet evolving into an unstable puff, an evolution that we corroborate by comparison with photographs and videos of actual vapers. On the grounds of all this theoretical modeling, we estimate for low-intensity vaping (practiced by 80–90% of vapers) the emission of 6–210 (median 39.9, median deviation 67.3) respiratory submicron droplets per puff and a horizontal distance spread of 1–2 m, with intense vaping possibly emitting up to 1000 droplets per puff in the submicron range with a distance spread over 2 m. The optical visibility of the ECA flow has important safety implications, as bystanders become instinctively aware of the scope and distance of possible direct contagion through the vaping jet.

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