Influence of ambient conditions on evaporation and transport of respiratory droplets in indoor environment

Pal, Ritam; Sarkar, Sourav; Mukhopadhyay, Achintya

doi:10.1016/j.icheatmasstransfer.2021.105750

Cited by 22 publications

(10 citation statements)

References 60 publications

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“…Fine infectious aerosols can travel for long distances in the air and can carry a sufficiently large viral load to cause infection in healthy subjects [ 23 , 28 ]. These infectious aerosols can originate from fine aerosols carrying sufficient viral loads [ 29 ], or be produced by larger particles with larger viral loads, who have undergone partial evaporation before settling to the ground [ 28 ].…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2

et al. 2023

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The COVID-19 pandemic due to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been plaguing the world since late 2019/early 2020 and has changed the way we function as a society, halting both economic and social activities worldwide. Classrooms, offices, restaurants, public transport, and other enclosed spaces that typically gather large groups of people indoors, and are considered focal points for the spread of the virus. For society to be able to go “back to normal”, it is crucial to keep these places open and functioning. An understanding of the transmission modes occurring in these contexts is essential to set up effective infection control strategies. This understanding was made using a systematic review, according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses statement (PRISMA) 2020 guidelines. We analyze the different parameters influencing airborne transmission indoors, the mathematical models proposed to understand it, and discuss how we can act on these parameters. Methods to judge infection risks through the analysis of the indoor air quality are described. Various mitigation measures are listed, and their efficiency, feasibility, and acceptability are ranked by a panel of experts in the field. Thus, effective ventilation procedures controlled by CO2-monitoring, continued mask wearing, and a strategic control of room occupancy, among other measures, are put forth to enable a safe return to these essential places.

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Section: Resultsmentioning

confidence: 99%

“…Thus, it is crucial to understand both the evaporation mechanisms and the parameters influencing them. Evaporation time depends strongly on the temperature and humidity of the ambient air, impacting the behavior of respiratory droplets [ 23 , 27 , 28 , 30 , 31 ]. The influences of these factors will be discussed below.…”

Section: Resultsmentioning

confidence: 99%

Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2

et al. 2023

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“…In this context, it is notable that out of a droplet and a droplet nuclei of the same size, the droplet nuclei is more harmful as it has surely been inherited from an initially larger droplet, thus exhibiting a very high viral load. 11 Moreover, the droplet nuclei basically consist of only the nonvolatile component, which in turn contains the pathogen. A significant number of suspended droplets evaporate to form droplet nuclei having sizes mostly in the range of 10–20 μ m after 10 s as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The droplet trajectories were calculated considering a turbulent round jet model. 11 Chong et al quantified the lifetime of respiratory droplets under different ambient humidity conditions using direct numerical solution (DNS). They have reported that the droplet lifetime can extend even up to 150 times at very high relative humidity (90%).…”

Section: Introductionmentioning

confidence: 99%

Risk assessment of COVID infection by respiratory droplets from cough for various ventilation scenarios inside an elevator: An OpenFOAM-based computational fluid dynamics analysis

Biswas

Pal

et al. 2022

Physics of Fluids

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Respiratory droplets—which may contain disease spreading virus—exhaled during speaking, coughing, or sneezing are one of the significant causes for the spread of the ongoing COVID-19 pandemic. The droplet dispersion depends on the surrounding air velocity, ambient temperature, and relative humidity. In a confined space like an elevator, the risk of transmission becomes higher when there is an infected person inside the elevator with other individuals. In this work, a numerical investigation is carried out in a three-dimensional domain resembling an elevator using OpenFoam. Three different modes of air ventilation, viz., quiescent, axial exhaust draft, and exhaust fan, have been considered to investigate the effect of ventilation on droplet transmission for two different climatic conditions (30 , 50% relative humidity and 10 , 90% relative humidity). The risk assessment is quantified using a risk factor based on the time-averaged droplet count present near the passenger's hand to head region (risky height zone). The risk factor drops from 40% in a quiescent scenario to 0% in an exhaust fan ventilation condition in a hot dry environment. In general, cold humid conditions are safer than hot dry conditions as the droplets settle down quickly below the risky height zone owing to their larger masses maintained by negligible evaporation. However, an exhaust fan renders the domain in a hot dry ambience completely safe (risk factor, 0%) in 5.5 s whereas it takes 7.48 s for a cold humid ambience.

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“…The diameter of the particles is assumed to be constant. Although evaporation effects can be important depending on the ambient conditions ( Pal et al, 2021 ), for the conditions considered in the present simulations, the effect of the progressive reduction of diameter due to evaporation is limited to the moderate size particles (32 μm) ( Fabregat, Gisbert, Vernet, Ferré, et al, 2021 ). Smaller particles, with smaller Stokes numbers, follow well the flow irrespectively of their diameter because of their small inertia.…”

Section: Physical Modelsmentioning

confidence: 99%

Effects of upper respiratory tract anatomy and head movement on the buoyant flow and particle dispersion generated in a violent expiratory event

Pallarès

Fabregat

Cito

2022

Journal of Aerosol Science

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Influence of ambient conditions on evaporation and transport of respiratory droplets in indoor environment

Cited by 22 publications

References 60 publications

Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2

Systematic Review of the Key Factors Influencing the Indoor Airborne Spread of SARS-CoV-2

Risk assessment of COVID infection by respiratory droplets from cough for various ventilation scenarios inside an elevator: An OpenFOAM-based computational fluid dynamics analysis

Effects of upper respiratory tract anatomy and head movement on the buoyant flow and particle dispersion generated in a violent expiratory event

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