Influence of pulmonary ventilation rate and breathing cycle period on the risk of cross‐infection

Ai, Zhengtao; Hashimoto, Kaho; Melikov, Arsen Krikor

doi:10.1111/ina.12589

Cited by 49 publications

(26 citation statements)

References 45 publications

(124 reference statements)

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“…This airflow interaction in the human body microenvironment is complex ( Melikov, 2015 ) and has a major impact on short-distance exposure ( Melikov and Ai, 2020 ). Research has shown that short-distance exposure in ventilated rooms occurs when the distance between the exposed occupant and the infected person is less than 1–1.5 m ( Ai and Melikov, 2018 , Ai et al, 2019 ). Long-distance exposure occurs at distances between occupants of more than 1–1.5 m when the pollution is more or less mixed with the air in the occupied zone.…”

Section: The Process Of Ventilation and Exposurementioning

confidence: 99%

Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors

Melikov

Markov

2020

Science of The Total Environment

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It is important that efficient measures to reduce the airborne transmission of respiratory infectious diseases (including COVID-19) should be formulated as soon as possible to ensure a safe easing of lockdown. Ventilation has been widely recognized as an efficient engineering control measure for airborne transmission. Room ventilation with an increased supply of clean outdoor air could dilute the expiratory airborne aerosols to a lower concentration level. However, sufficient increase is beyond the capacity of most of the existing mechanical ventilation systems that were designed to be energy efficient under non-pandemic conditions. We propose an improved control strategy based on source control, which would be achieved by implementing intermittent breaks in room occupancy, specifically that all occupants should leave the room periodically and the room occupancy time should be reduced as much as possible. Under the assumption of good mixing of clean outdoor supply air with room air, the evolution of the concentration in the room of aerosols exhaled by infected person(s) is predicted. The risk of airborne cross-infection is then evaluated by calculating the time-averaged intake fraction. The effectiveness of the strategy is demonstrated for a case study of a typical classroom. This strategy, together with other control measures such as continuous supply of maximum clean air, distancing, face-to-back layout of workstations and reducing activities that increase aerosol generation (e.g., loudly talking and singing), is applicable in classrooms, offices, meeting rooms, conference rooms, etc.

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Section: The Process Of Ventilation and Exposurementioning

confidence: 99%

Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors

Melikov

Markov

2020

Science of The Total Environment

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“…This has been confirmed by experiments and modelling studies of aerosol dynamics. 17 , [28] , [29] , [30] , [31] , [32] , [33] …”

Section: Introductionmentioning

confidence: 99%

Dismantling myths on the airborne transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)

Tang

Bahnfleth

Bluyssen

et al. 2021

Journal of Hospital Infection

309

288

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stimulate revision of the science in the light of current evidence. Six 'myths' are presented, explained and ultimately refuted on the basis of recently published papers and expert opinion from previous work related to similar viruses. There is little doubt that SARS-CoV-2 is transmitted via a range of airborne particle sizes subject to all the usual ventilation parameters and human behaviour. Experts from specialties encompassing aerosol studies, ventilation, engineering, physics, virology and clinical medicine have joined together to produce this review to consolidate the evidence for airborne transmission mechanisms, and offer justification for modern strategies for prevention and control of COVID-19 in health care and the community.

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“…However, to date, most of the thermo-fluid dynamic analyses performed on this very complex subject are limited to non-pathogen carrying droplet emission and/or simulate simplified conditions (e.g. constant emission, steady-state analyses) ( Ai et al, 2019 ; Ai and Melikov, 2018 ).…”

Section: Introductionmentioning

confidence: 99%

Close proximity risk assessment for SARS-CoV-2 infection

Cortellessa

Stabile

Arpino

et al. 2021

Science of The Total Environment

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Although the interpersonal distance represents an important parameter affecting the risk of infection due to respiratory viruses, the mechanism of exposure to exhaled droplets remains insufficiently characterized. In this study, an integrated risk assessment is presented for SARS-CoV-2 close proximity exposure between a speaking infectious subject and a susceptible subject. It is based on a three-dimensional transient numerical model for the description of exhaled droplet spread once emitted by a speaking person, coupled with a recently proposed SARS-CoV-2 emission approach. Particle image velocimetry measurements were conducted to validate the numerical model. The contribution of the large droplets to the risk is barely noticeable only for distances well below 0.6 m, whereas it drops to zero for greater distances where it depends only on airborne droplets. In particular, for short exposures (10 s) a minimum safety distance of 0.75 m should be maintained to lower the risk below 0.1%; for exposures of 1 and 15 min this distance increases to about 1.1 and 1.5 m, respectively. Based on the interpersonal distances across countries reported as a function of interacting individuals, cultural differences, and environmental and sociopsychological factors, the approach presented here revealed that, in addition to intimate and personal distances, particular attention must be paid to exposures longer than 1 min within social distances (of about 1 m).

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Influence of pulmonary ventilation rate and breathing cycle period on the risk of cross‐infection

Cited by 49 publications

References 45 publications

Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors

Intermittent occupancy combined with ventilation: An efficient strategy for the reduction of airborne transmission indoors

Dismantling myths on the airborne transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2)

Close proximity risk assessment for SARS-CoV-2 infection

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