Estimation of airborne viral emission: Quanta emission rate of SARS-CoV-2 for infection risk assessment

Buonanno, Giorgio; Stabile, Luca; Morawska, Lidia

doi:10.1016/j.envint.2020.105794

Cited by 616 publications

(921 citation statements)

References 23 publications

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“…A similar effect has been suggested to occur if a low volume of virions are transmitted between masked individuals when social distancing is being practiced. [68] individuals to be higher than typical [20,21,29] . The inference of high viral loads in prior work stems from an assumption of low volumes of aerosols emitted by index patients (order 1-10 nL/hour) [20,21] .…”

Section: Conclusion and Suggestions For Future Researchmentioning

confidence: 72%

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19

Prentiss¹,

Chu²,

Berggren³

2020

Preprint

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We study transmission of COVID-19 using five well-documented case studies : a Washington state church choir, a Korean call center, a Korean exercise class, and two different Chinese bus trips. In all cases the likely index patients were pre-symptomatic or mildly symptomatic, which is when infective patients are most likely to interact with large groups of people. An estimate of N 0 , the characteristic number of COVID-19 virions needed to induce infection in each case, is found using a simple physical model of airborne transmission. We find that the N 0 values are similar for five COVID-19 superspreading cases (~300-2,000 viral copies) and of the same order as influenza A. Consistent with the recent results of Goyal et al , these results suggest that viral loads relevant to infection from presymptomatic or mildly symptomatic individuals may fall into a narrow range, and that exceptionally high viral loads are not required to induce a superspreading event [1,2] . Rather, t he accumulation of infective aerosols exhaled by a typical pre-symptomatic or mildly symptomatic patient in a confined, crowdedspace (amplified by poor ventilation, particularly activity like exercise or singing, or lack of masks) for exposure times as short as one hour are sufficient. We calculate that talking and breathing release ~460 N 0 and ~10 N 0 (quanta)/hour, respectively, providing a basis to estimate the risks of everyday activities. Finally, we provide a calculation which motivates the observation that fomites appear to account for a smallpercentage of total COVID-19 infection events.

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Section: Conclusion and Suggestions For Future Researchmentioning

confidence: 72%

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19

Prentiss¹,

Chu²,

Berggren³

2020

Preprint

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“…37 A forward model was used to estimate a large range of estimated quanta emission rates for SARS-COV-2, depending on activity level and respiratory activity: 10.5-1030 quanta h -1 . 24 To explore the influence of changing the loss rate on the probability of infection, we performed sensitivity simulations in which we varied the loss rate. In these simulations, we used the mean emission rate of E = 970 q h -1 and a constant volumetric breathing rate of Qb = 1.0 m 3 h -1 .…”

Section: Resultsmentioning

confidence: 99%

Transmission of SARS‐CoV‐2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event

et al. 2020

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During the 2020 COVID-19 pandemic, an outbreak occurred following attendance of a symptomatic index case at a regular weekly rehearsal on 10 March of the Skagit Valley Chorale (SVC). After that rehearsal, 53 members of the SVC among 61 in attendance were confirmed or strongly suspected to have contracted COVID-19 and two died. Transmission by the airborne route is likely. It is vital to identify features of cases such as this so as to better understand the factors that promote superspreading events. Based on a conditional assumption that transmission during this outbreak was by inhalation of respiratory aerosol, we use the available evidence to infer the emission rate of airborne infectious quanta from the primary source. We also explore how the risk of infection would vary with several influential factors: the rates of removal of respiratory aerosol by ventilation; deposition onto surfaces; and viral decay. The results indicate an emission rate of the order of a thousand quanta per hour (mean [interquartile range] for this event = 970 [680-1190] quanta per hour) and demonstrate that the risk of infection is modulated by ventilation conditions, occupant density, and duration of shared presence with an infectious individual.

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“…Respiratory infections such as COVID-19 are transmitted through droplets (5 to 10 μm) and aerosols (smaller than 5 μm) exhaled from infected individuals when breathing, speaking, coughing, and sneezing (Prather, Wang, and Schooley 2020). Although there is still plenty of uncertainty about the various ways in which COVID-19 contagion occurs (Leung et al 2020;Han et al 2020), airborne transmission in closed environments has been established by several authors (Morawska and Cao 2020;Shen et al 2020;Prather, Wang, and Schooley 2020;Buonanno, Stabile, and Morawska 2020). Consequently, closed environments are generally riskier than open environments (Nishiura et al 2020;Qian et al 2020).…”

Section: Covid-19 Effects and New Rules For The Use Of Public Transpomentioning

confidence: 99%

COVID-19 and Public Transportation: Current Assessment, Prospects, and Research Needs

Tirachini

Cats

2020

JPT

578

437

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The COVID-19 pandemic poses a great challenge for contemporary public transportation worldwide, resulting from an unprecedented decline in demand and revenue. In this paper, we synthesize the state-of-the-art, up to early June 2020, on key developments regarding public transportation and the COVID-19 pandemic, including the different responses adopted by governments and public transportation agencies around the world, and the research needs pertaining to critical issues that minimize contagion risk in public transportation in the so-called post-lockdown phase. While attempts at adherence to physical distancing (which challenges the very concept of mass public transportation) are looming in several countries, the latest research shows that for closed environments such as public transportation vehicles, the proper use of face masks has significantly reduced the probability of contagion. The economic and social effects of the COVID-19 outbreak in public transportation extend beyond service performance and health risks to financial viability, social equity, and sustainable mobility. There is a risk that if the public transportation sector is perceived as poorly transitioning to post-pandemic conditions, that viewing public transportation as unhealthy will gain ground and might be sustained. To this end, this paper identifies the research needs and outlines a research agenda for the public health implications of alternative strategies and scenarios, specifically measures to reduce crowding in public transportation. The paper provides an overview and an outlook for transit policy makers, planners, and researchers to map the state-of-affairs and research needs related to the impacts of the pandemic crisis on public transportation. Some research needs require urgent attention given what is ultimately at stake in several countries: restoring the ability of public transportation systems to fulfill their societal role.

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Estimation of airborne viral emission: Quanta emission rate of SARS-CoV-2 for infection risk assessment

Cited by 616 publications

References 23 publications

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19

Transmission of SARS‐CoV‐2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event

COVID-19 and Public Transportation: Current Assessment, Prospects, and Research Needs

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Estimation of airborne viral emission: Quanta emission rate of SARS-CoV-2 for infection risk assessment

Cited by 616 publications

References 23 publications

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate Nº for Airborne Transmission of COVID-19

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate Nº for Airborne Transmission of COVID-19

Transmission of SARS‐CoV‐2 by inhalation of respiratory aerosol in the Skagit Valley Chorale superspreading event

COVID-19 and Public Transportation: Current Assessment, Prospects, and Research Needs

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Product

Resources

About

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19

Superspreading Events Without Superspreaders: Using High Attack Rate Events to Estimate N_º for Airborne Transmission of COVID-19