Falling Dynamics of SARS-CoV-2 as a Function of Respiratory Droplet Size and Human Height

Aydin, Mehmet; Evrendilek, Fatih; Savas, Seckin Aydin; Aydın, İsmail Erkan; Evrendilek, Deniz Eren

doi:10.1007/s40846-020-00575-y

Cited by 13 publications

(23 citation statements)

References 6 publications

(10 reference statements)

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“… NA j World Health Organization (2018) 43 Official guideline Acquiring respiratory diseases was associated with crowding. NA K Mehmet Aydin (2020) 35 Comparative study The horizontal distance travelled by droplet was 1.7 m due to breathing or talking. NA l Tianxiang (2020) 44 Cross-sectional study Routine disinfection procedures were effective in reducing the potential risk of healthcare associated infection.…”

Section: Resultsmentioning

confidence: 99%

A Semi-Quantitative Risk Assessment and Management Strategies on COVID-19 Infection to Outpatient Health Care Workers in the Post-Pandemic Period

Wang¹,

Wang²,

Zhao³

et al. 2021

RMHP

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Background In the pandemic of COVID-19, due to asymptomatic patients and high personnel fluidity in outpatient clinics, health care workers (HCWs) in outpatients were facing severe threat from infection. There is an urgent need for a risk assessment to recognize and prevent infection risks. Purpose To establish a semi-quantitative risk assessment model on COVID-19 infections for HCWs in outpatient departments, and apply it to practices. Further to provide infection risk management strategies to reduce infection threats in the post-pandemic of COVID-19. Methods We used the method of Brainstorm, Literature study and Analytic Hierarchy Process (AHP) for risk factors selection and model construction, we also created corresponding indicators for each risk factors, in order to collect data in assessment practice. Results Eighteen risk factors were recognized and selected for model construction, by scatter plot, these risk factors had been classified into four parts, spanned the scopes of diagnosis and treatment, environment, personal protection and emergency handling, with specific management suggestions provided. In the practice, outpatient clinics were divided into three risk levels, 5 clinics in high risk level, 9 in medium risk level and 11 in low risk level. Conclusion A proper comprehensive risk assessment model for COVID-19 infections has been successfully established. With the model, the ability to COVID-19 prevention in outpatients can be easily evaluated. The strategies on disinfection, surveillance and personal protection were also valuable references in the post-pandemic of COVID-19.

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Section: Resultsmentioning

confidence: 99%

A Semi-Quantitative Risk Assessment and Management Strategies on COVID-19 Infection to Outpatient Health Care Workers in the Post-Pandemic Period

Wang¹,

Wang²,

Zhao³

et al. 2021

RMHP

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“…The deterministic models of both spread and falling dynamics generate outputs fully determined by their parameters and initial condition values (Das et al, 2020 ). Given the conditions of terminal/constant velocity, the following two approaches can be adopted (Aydin et al, 2020a ). First, the combination of the Newton’s and modern lift equations yields the terminal velocity of the particle as follows: where is the downward terminal velocity (m s −1 ), is the particle mass (kg), is the gravitational acceleration (9.81 m s −2 ), is a shape-dependent coefficient such as 0.47 for water droplets of a spherical shape which was assumed as 1.99 for a single isolated SARS-CoV-2 due to its spikes, is the air density (1.2041 kg m −3 at 20 °C and 1 atm); and is the cross-surface area (m 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…The diameter of the virus varies between 60 and 140 nanometer (nm) with an average of 100 nm (1 nm = 10 −9 m). The volume and mass of a single virus were estimated at 5.236 × 10 −22 m 3 and 7.07 × 10 −19 kg, respectively (Aydin et al, 2020a ; Zhu et al, 2020). Several studies (Anchordoqui & Chudnovsky, 2020 ; Aydin et al, 2020a ; Gorbunov, 2020 ) determined its falling time and velocity regimes with(out) a respiratory droplet.…”

Section: Introductionmentioning

confidence: 99%

“…The volume and mass of a single virus were estimated at 5.236 × 10 −22 m 3 and 7.07 × 10 −19 kg, respectively (Aydin et al, 2020a ; Zhu et al, 2020). Several studies (Anchordoqui & Chudnovsky, 2020 ; Aydin et al, 2020a ; Gorbunov, 2020 ) determined its falling time and velocity regimes with(out) a respiratory droplet. When SARS-CoV-2 is transmitted through a respiratory droplet in the air, a better quantification of its falling dynamics entails the consideration of its evaporation regimes (Chong et al, 2021 ).…”

Section: Introductionmentioning

confidence: 99%

“…Aydin et al ( 2020a ) reported that the two models significantly differed in the falling time predictions of a SARS-CoV-2-laden respiratory droplet under the gravity with air resistance, in particular, when the droplet diameter was 100 and 500 µm (µm). They also concluded that the Newtonian lift equation and Stokes’s law were applicable mostly to the droplet diameter 237.5 µm and 237.5 µm, respectively.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A model for indoor motion dynamics of SARS-CoV-2 as a function of respiratory droplet size and evaporation

Aydin

Savas

Evrendilek

et al. 2021

Environ Monit Assess

Self Cite

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A simplified model has been devised to estimate the falling dynamics of severe acute respiratory syndrome corona-virus 2 (SARS-CoV-2)-laden droplets in an indoor environment. Our estimations were compared to existing literature data. The spread of SARS-CoV-2 is closely coupled to its falling dynamics as a function of respiratory droplet diameter (1 to 2000 μm) of an infected person and droplet evaporation. The falling time of SARS-CoV-2 with a respiratory droplet diameter of about 300 μm from a height of 1.7 m remained almost the same among the Newtonian lift equation, Stokes’s law, and our simplified model derived from them so as to account for its evaporation. The evaporative demand peaked at midday which was ten times that at midnight. The evaporating droplets 6 μm lost their water content rapidly, making their lifetimes in the air shorter than their falling times. The droplets 6 μm were able to evaporate completely and remained in the air for about 5 min as droplet nuclei with SARS-CoV-2.

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Influence of indoor environmental conditions on airborne transmission and lifetime of sneeze droplets in a confined space: a way to reduce COVID-19 spread

Bahramian

2023

Environ Sci Pollut Res

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Effects of indoor temperature ( T ∞ ) and relative humidity ( RH ∞ ) on the airborne transmission of sneeze droplets in a confined space were studied over the T ∞ range of 15–30 °C and RH ∞ of 22–62%. In addition, a theoretical evaporation model was used to estimate the droplet lifetime based on experimental data. The results showed that the body mass index (BMI) of the participants played an important role in the sneezing jet velocity, while the impact of the BMI and gender of participants was insignificant on the size distribution of droplets. At a critical relative humidity RH ∞,crit of 46%, the sneezing jet velocity and droplet lifetime were roughly independent of T ∞ . At RH ∞ < RH ∞,crit , the sneezing jet velocity decreased by increasing T ∞ from 15 to 30 °C, while its trend was reversed at RH ∞ > RH ∞,crit . The maximum spreading distance of aerosols increased by decreasing the RH ∞ and increasing T ∞ , while the droplet lifetime increased by decreasing T ∞ at RH ∞ > RH ∞,crit . The mean diameter of aerosolized droplets was less affected by T ∞ than the large droplets at RH ∞ < RH ∞,crit , while the mean diameter and number fraction of aerosols were more influenced by RH ∞ than the T ∞ in the range of 46% ≤ RH ∞ ≤ 62%. In summary, this study suggests suitable indoor environmental conditions by considering the transmission rate and lifetime of respiratory droplets to reduce the spread of COVID-19. Graphical abstract Supplementary Information The online version contains supplementary material available at 10.1007/s11356-023-25421-x.

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Falling Dynamics of SARS-CoV-2 as a Function of Respiratory Droplet Size and Human Height

Cited by 13 publications

References 6 publications

A Semi-Quantitative Risk Assessment and Management Strategies on COVID-19 Infection to Outpatient Health Care Workers in the Post-Pandemic Period

A Semi-Quantitative Risk Assessment and Management Strategies on COVID-19 Infection to Outpatient Health Care Workers in the Post-Pandemic Period

A model for indoor motion dynamics of SARS-CoV-2 as a function of respiratory droplet size and evaporation

Influence of indoor environmental conditions on airborne transmission and lifetime of sneeze droplets in a confined space: a way to reduce COVID-19 spread

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