A numerical study of the effects of ambient temperature and humidity on the particle growth and deposition in the human airway

Xu, Chang; Zheng, Xin; Shen, Shifei

doi:10.1016/j.envres.2021.111751

Cited by 16 publications

(10 citation statements)

References 68 publications

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Section: Resultssupporting

confidence: 74%

“…It was shown that supersaturation can lead to enhanced deposition of inhaled ambient aerosols, infectious aerosols and air pollutants in the human airways (Ishmatov, 2017a;Ishmatov, 2020b). Xu et al (2021) also confirmed this aspect in the study with the help of numerical experiments. Moreover, role of effect of supersaturation in a critical cooling of local areas in the human upper airways was discussed, and this involves cold stress and reducing, as a consequence, the antiviral immune response of the airway epithelial cells.…”

Section: Future Directions and Limitationssupporting

confidence: 54%

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Mechanistic view on the influence of fluctuations in outdoor temperature on the worsening of the course of the disease and hospitalizations associated with the SARS-CoV-2 Omicron wave in 2022 in the Tomsk region, Russia

Ishmatov

Bart

Yakovlev

2023

Preprint

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It is well known that low air temperatures negatively affect the human respiratory system and can suppress protective mechanisms in airways epithelial cells. In this study, we put forward the hypothesis that the compromised airway epithelium of infected persons can be extremely sensitive to external influences and therefore can be used as an indicator and serve to investigate the impact of low air temperatures (as and other external factors) on the respiratory system. Here we supposed that a short-term impact of drop in outdoor temperature on the compromised airway epithelium should lead to increased symptoms and severity of the disease. We have analyzed a short-term impact of the air temperature drop on the worsening of disease in patients with COVID-19 (indicated by bursts of daily hospitalizations), which fell on the main epidemic wave in 2022 associated with SARS-CoV-2 Omicron variant. It was found that even a small and/or short-term impact of drop in outdoor daily temperatures can lead to increased symptoms and severity of the disease (COVID-19). We have identified 14 characteristic points (days) where the temperature drop was more than 3 degrees during the main pandemic wave in 2022. It was shown that each characteristic points clearly associated with characteristic bursts in the number of daily hospitalizations with a time lag of 1-2 days. Thus, it was found that the results of the study can be used in predicting a sudden increase in the number of hospitalizations, which can be used to timely warn clinics and medical hospitals for an increase in the number of seriously ill patients. The findings can be used to improve systems to prevent additional risks connected with impact of drop in air temperature on worsening disease in patients and infected people who do not have or have mild or subtle symptoms of the disease - especially during an epidemic or pandemic wave.

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Section: Resultssupporting

confidence: 74%

Section: Future Directions and Limitationssupporting

confidence: 54%

Mechanistic view on the influence of fluctuations in outdoor temperature on the worsening of the course of the disease and hospitalizations associated with the SARS-CoV-2 Omicron wave in 2022 in the Tomsk region, Russia

Ishmatov

Bart

Yakovlev

2023

Preprint

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“…Here, the DF is defined as the ratio of the deposited aerosol number (𝑁 𝑑𝑒𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 ) to the total aerosol number (𝑁 𝑡𝑜𝑡𝑎𝑙 ), i.e., 𝐷𝐹 = (𝑁 𝑑𝑒𝑝𝑜𝑠𝑖𝑡𝑖𝑜𝑛 /𝑁 𝑡𝑜𝑡𝑎𝑙 ) × 100% (Cui et al 2023;Feng and Cui 2023;Narayanan et al 2021;Xu et al 2021). The inertial factor (𝐼 = 𝜌 𝑝 𝑑 𝑝 2 𝑄), defined as the product of aerosol density, the square of diameter and the rate of airflow, is also used for this evaluation (Chen et al 2017;Liu 2020;Ghahramani et al 2014;Chen et al 2021).…”

Section: Validation Of Methodologymentioning

confidence: 99%

“…More details about this model can be found in our previous works (Cui et al 2023;Feng and Cui 2023). To account for thermal effects, the shell model is extended outward by 1 mm to represent the mucus layer (Chen et al 2017;Narayanan et al 2021;Xu et al 2021). Due to the irregular morphology of the airway model, an unstructured polyhedral mesh is chosen to reduce the number of grids and conserve computational resources (Cui and Li 2021;Narayanan et al 2021).…”

Section: Geometrical Model and Meshmentioning

confidence: 99%

“…The velocity at the airway wall is set to no-slip, and the temperature is set to 37 ℃ (Xu 2019;Feng and Cui 2023;Xu et al 2021). The pressure and momentum equations of the airflow are discretized using the second-order upwind scheme, and the equations are solved using the Simple (Semi-Implicit Method for Pressure Linked Equations) algorithm in ANSYS Fluent until convergence is achieved, with an iterative error less than 10 -5 .…”

Section: Simulation Setupsmentioning

confidence: 99%

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Numerical investigations of exhaling respiratory aerosol from inside of the human respiratory tract

Feng,

Wang,

Cui

2024

Preprint

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The characteristics of exhaled aerosol outside the human respiratory airway are of significant importance in understanding virus transmission, yet they remain poorly understood. In order to effectively prevent and control the spread of respiratory infectious diseases, this study numerically investigates the exhaling characteristics of respiratory aerosol exhaled from the bronchus or larynx of a human upper airway model. This is achieved using the Euler-Lagrange method and considering various aerosol diameters (dp=0.1, 0.3, 0.5, and 1-20 μm) as well as five expiratory flow intensities (Q=15, 30, 60, 90, and 120 L/min). The important findings of this study are as follows: (1) Expiratory airflow exhibits complex flow phenomena, including jet-flow, flow separations, and vortex structures, with their characteristics being influenced by the expiratory flow intensities. (2) The exhaling characteristics of aerosol vary depending on the combined effects of expiratory flow intensities, aerosol diameters, and initial exhaled locations from either the bronchus or larynx. (3) A critical diameter (dc) is identified to represent the size at which aerosol can effectively exit the respiratory airway and potentially pose a transmission risk. This critical diameter is identical for aerosol exhaled from both the bronchus and larynx under the same expiratory flow intensity, but it decreases as the expiratory flow intensity increases. In conclusion, expiratory flow intensity is the most critical factor in determining whether aerosol droplets can be expelled from the respiratory airway, as well as influencing the critical diameter (dc) for aerosol droplets initially located in/after the larynx.

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Influencing factors of particle deposition in the human nasal cavity

Guo,

Tang,

et al. 2024

Laryngoscope Investig Oto

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ObjectiveTo review the existing literature on the application of computational fluid dynamics methods to study nasal particle deposition and to summarize and analyze the factors affecting nasal particle deposition in order to provide theoretical references for the development of future transnasal drug delivery devices and the prevention of respiratory‐related diseases.Data SourcePubMed and CNKI databases.MethodsA search of all current literature (up to and including February 2023) was conducted. Search terms related to the topic of factors influencing nasal particle deposition were identified, and queries were conducted to identify relevant articles.ResultsBoth the properties of the particles themselves and the environmental conditions external to the particles can affect particle deposition in the nasal cavity, with particle deposition showing a positive correlation with particle size, particle density, and airflow velocity, with increasing subject age leading to a decrease in deposition, and with the relationship between airflow temperature and humidity still requiring more research to further explore.ConclusionsWith the popularity of computational fluid dynamics, more and more scholars have applied computational fluid dynamics technology to explore the influence of different parameters on particle deposition. By summarizing and analyzing the influence law of various factors on deposition, it can provide a theoretical basis for the future development and application of transnasal drug delivery devices and the prevention of respiratory‐related diseases, which makes a significant contribution to the optimization of clinical disease prevention and treatment.Level of EvidenceNA.

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A numerical study of the effects of ambient temperature and humidity on the particle growth and deposition in the human airway

Cited by 16 publications

References 68 publications

Mechanistic view on the influence of fluctuations in outdoor temperature on the worsening of the course of the disease and hospitalizations associated with the SARS-CoV-2 Omicron wave in 2022 in the Tomsk region, Russia

Mechanistic view on the influence of fluctuations in outdoor temperature on the worsening of the course of the disease and hospitalizations associated with the SARS-CoV-2 Omicron wave in 2022 in the Tomsk region, Russia

Numerical investigations of exhaling respiratory aerosol from inside of the human respiratory tract

Influencing factors of particle deposition in the human nasal cavity

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