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Zhou M, Zou J. A dynamical overview of droplets in the transmission of respiratory infectious diseases. PHYSICS OF FLUIDS (WOODBURY, N.Y. : 1994) 2021; 33:031301. [PMID: 33897237 PMCID: PMC8061903 DOI: 10.1063/5.0039487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 12/29/2020] [Indexed: 05/04/2023]
Abstract
The outbreak of the coronavirus disease has drawn public attention to the transmission of infectious pathogens, and as major carriers of those pathogens, respiratory droplets play an important role in the process of transmission. This Review describes respiratory droplets from a physical and mechanical perspective, especially their correlation with the transmission of infectious pathogens. It covers the important aspects of (i) the generation and expulsion of droplets during respiratory activities, (ii) the transport and evolution of respiratory droplets in the ambient environment, and (iii) the inhalation and deposition of droplets in the human respiratory tract. State-of-the-art experimental, computational, and theoretical models and results are presented, and the corresponding knowledge gaps are identified. This Review stresses the multidisciplinary nature of its subject and appeals for collaboration among different fields to fight the present pandemic.
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Affiliation(s)
- Maoying Zhou
- School of Mechanical Engineering, Hangzhou Dianzi
University, Hangzhou, Zhejiang 310027, China
| | - Jun Zou
- State Key Laboratory of Fluid Power and Mechatronic Systems,
Zhejiang University, Hangzhou, Zhejiang 310027,
China
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A Review of Respiratory Anatomical Development, Air Flow Characterization and Particle Deposition. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17020380. [PMID: 31935991 PMCID: PMC7014067 DOI: 10.3390/ijerph17020380] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 12/31/2019] [Accepted: 12/31/2019] [Indexed: 12/20/2022]
Abstract
The understanding of complex inhalation and transport processes of pollutant particles through the human respiratory system is important for investigations into dosimetry and respiratory health effects in various settings, such as environmental or occupational health. The studies over the last few decades for micro- and nanoparticle transport and deposition have advanced the understanding of drug-aerosol impacts in the mouth-throat and the upper airways. However, most of the Lagrangian and Eulerian studies have utilized the non-realistic symmetric anatomical model for airflow and particle deposition predictions. Recent improvements to visualization techniques using high-resolution computed tomography (CT) data and the resultant development of three dimensional (3-D) anatomical models support the realistic representation of lung geometry. Yet, the selection of different modelling approaches to analyze the transitional flow behavior and the use of different inlet and outlet conditions provide a dissimilar prediction of particle deposition in the human lung. Moreover, incorporation of relevant physical and appropriate boundary conditions are important factors to consider for the more accurate prediction of transitional flow and particle transport in human lung. This review critically appraises currently available literature on airflow and particle transport mechanism in the lungs, as well as numerical simulations with the aim to explore processes involved. Numerical studies found that both the Euler–Lagrange (E-L) and Euler–Euler methods do not influence nanoparticle (particle diameter ≤50 nm) deposition patterns at a flow rate ≤25 L/min. Furthermore, numerical studies demonstrated that turbulence dispersion does not significantly affect nanoparticle deposition patterns. This critical review aims to develop the field and increase the state-of-the-art in human lung modelling.
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Wei T, Tang M. Biological effects of airborne fine particulate matter (PM 2.5) exposure on pulmonary immune system. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2018; 60:195-201. [PMID: 29734103 DOI: 10.1016/j.etap.2018.04.004] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Revised: 04/02/2018] [Accepted: 04/03/2018] [Indexed: 05/21/2023]
Abstract
Airborne fine particulate matter (PM2.5) attracts more and more attention due to its environmental effects. The immune system appears to be a most sensitive target organ for the environmental pollutants. Inhaled PM2.5 can deposit in different compartments in the respiratory tract and interact with epithelial cells and resident immune cells. Exposed to PM2.5 can induce local or systematic inflammatory responses. This review focus on the effects of respiratory tract exposed to PM2.5. Firstly, we introduced the major emission sources, basic characteristics of PM2.5 and discussed its immunoadjuvant potential. Secondly, we elaborated the immune cells in the respiratory tract and the deposition of PM2.5 regarding the structural characteristics of the respiratory tract. Furthermore, we summarized the in vivo/vitro studies that revealed the immunotoxic effects of PM2.5 exposure to pulmonary cellular effectors and explored the contribution of PM2.5 exposure to the Th1/Th2 balance.
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Affiliation(s)
- Tingting Wei
- Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, & Collaborative Innovation Center of Suzhou Nano Science and Technology, Southeast University, Nanjing 210009, PR China; Jiangsu key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210009, PR China
| | - Meng Tang
- Key Laboratory of Environmental Medicine and Engineering, Ministry of Education, School of Public Health, & Collaborative Innovation Center of Suzhou Nano Science and Technology, Southeast University, Nanjing 210009, PR China; Jiangsu key Laboratory for Biomaterials and Devices, Southeast University, Nanjing 210009, PR China.
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DeGroot CT, Straatman AG. A Conjugate Fluid-Porous Approach for Simulating Airflow in Realistic Geometric Representations of the Human Respiratory System. J Biomech Eng 2015; 138:4032113. [PMID: 26630498 DOI: 10.1115/1.4032113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 11/08/2022]
Abstract
Simulation of flow in the human lung is of great practical interest as a means to study the detailed flow patterns within the airways for many physiological applications. While computational simulation techniques are quite mature, lung simulations are particularly complicated due to the vast separation of length scales between upper airways and alveoli. Many past studies have presented numerical results for truncated airway trees, however, there are significant difficulties in connecting such results with respiratory airway models. This article presents a new modeling paradigm for flow in the full lung, based on a conjugate fluid-porous formulation where the upper airway is considered as a fluid region with the remainder of the lung being considered as a coupled porous region. Results are presented for a realistic lung geometry obtained from computed tomography (CT) images, which show the method's potential as being more efficient and practical than attempting to directly simulate flow in the full lung.
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Numerical Simulation Study on Airflow Structural Characteristics and Vortex Evolution in Human Mouth-Throat Model. ACTA ACUST UNITED AC 2014. [DOI: 10.4028/www.scientific.net/amm.627.115] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Large eddy simulation was used to simulate the airflow movement and vortex evolution in human mouth-throat model in the conditions of the low intensive respiratory patterns, and the airflow structural characteristic and vortex evolution in mouth-throat model was discussed. The results show that two velocity growth points generated in pharyngeal and laryngeal region; the airflow separates in region near the pharynx and the separation zone appears near the anterior wall of pharynx; A turbulence jet appears in the glottal region and the airflow; the jets formatting in pharynx and laryngeal lead to two vorticity growth regions; flat vortex appeared in the throat; a curved vortex like the trachea wall appeared in the anterior wall of trachea, and nearly symmetric reverse vortex pairs appeared in the trachea.
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Abstract
The human body interacts with the environment in many different ways. The lungs interact with the external environment through breathing. The enormously large surface area of the lung with its extremely thin air-blood barrier is exposed to particles suspended in the inhaled air. The particle-lung interaction may cause deleterious effects on health if the inhaled pollutant aerosols are toxic. Conversely, this interaction can be beneficial for disease treatment if the inhaled particles are therapeutic aerosolized drugs. In either case, an accurate estimation of dose and sites of deposition in the respiratory tract is fundamental to understanding subsequent biological response, and the basic physics of particle motion and engineering knowledge needed to understand these subjects is the topic of this article. A large portion of this article deals with three fundamental areas necessary to the understanding of particle transport and deposition in the respiratory tract. These are: (i) the physical characteristics of particles, (ii) particle behavior in gas flow, and (iii) gas-flow patterns in the respiratory tract. Other areas, such as particle transport in the developing lung and in the diseased lung are also considered. The article concludes with a summary and a brief discussion of areas of future research.
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Affiliation(s)
- Akira Tsuda
- Harvard School of Public Health, Boston, Massachusetts
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Jacob RE, Carson JP, Thomas M, Einstein DR. Dynamic multiscale boundary conditions for 4D CT of healthy and emphysematous rats. PLoS One 2013; 8:e65874. [PMID: 23799057 PMCID: PMC3683027 DOI: 10.1371/journal.pone.0065874] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 04/29/2013] [Indexed: 11/30/2022] Open
Abstract
Changes in the shape of the lung during breathing determine the movement of airways and alveoli, and thus impact airflow dynamics. Modeling airflow dynamics in health and disease is a key goal for predictive multiscale models of respiration. Past efforts to model changes in lung shape during breathing have measured shape at multiple breath-holds. However, breath-holds do not capture hysteretic differences between inspiration and expiration resulting from the additional energy required for inspiration. Alternatively, imaging dynamically--without breath-holds--allows measurement of hysteretic differences. In this study, we acquire multiple micro-CT images per breath (4DCT) in live rats, and from these images we develop, for the first time, dynamic volume maps. These maps show changes in local volume across the entire lung throughout the breathing cycle and accurately predict the global pressure-volume (PV) hysteresis. Male Sprague-Dawley rats were given either a full- or partial-lung dose of elastase or saline as a control. After three weeks, 4DCT images of the mechanically ventilated rats under anesthesia were acquired dynamically over the breathing cycle (11 time points, ≤100 ms temporal resolution, 8 cmH2O peak pressure). Non-rigid image registration was applied to determine the deformation gradient--a numerical description of changes to lung shape--at each time point. The registration accuracy was evaluated by landmark identification. Of 67 landmarks, one was determined misregistered by all three observers, and 11 were determined misregistered by two observers. Volume change maps were calculated on a voxel-by-voxel basis at all time points using both the Jacobian of the deformation gradient and the inhaled air fraction. The calculated lung PV hysteresis agrees with pressure-volume curves measured by the ventilator. Volume maps in diseased rats show increased compliance and ventilation heterogeneity. Future predictive multiscale models of rodent respiration may leverage such volume maps as boundary conditions.
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Affiliation(s)
- Richard E Jacob
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
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Martins LD, Martins JA, Freitas ED, Mazzoli CR, Gonçalves FLT, Ynoue RY, Hallak R, Albuquerque TTA, Andrade MDF. Potential health impact of ultrafine particles under clean and polluted urban atmospheric conditions: a model-based study. AIR QUALITY, ATMOSPHERE, & HEALTH 2010; 3:29-39. [PMID: 20376166 PMCID: PMC2844959 DOI: 10.1007/s11869-009-0048-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Accepted: 06/17/2009] [Indexed: 05/29/2023]
Abstract
The main goal of this study was to improve the knowledge of ultrafine particle number distributions in large urban areas and also to call the attention to the importance of these particles on assessing health risks. Measurements of aerosol size distributions were performed during 2 weeks, with distinct pollutant concentrations (polluted and clean periods), on the rooftop of a building located in downtown of the megacity of São Paulo, Brazil. CO, NO(2), PM(10), SO(2), and O(3) concentrations and meteorological variables were also used. Aerosol size distribution measurements showed that geometric mean diameters of the size spectra in the polluted period are on average considerably larger than those in the clean one. Besides the fact that total number of ultrafine particles did not show significant differences, during the polluted period, geometric mean diameter was larger than during the clean one. The results of a mathematical model of particle deposition on human respiratory tract indicated a more significant effect of smaller particles fraction of the spectra, which predominate under clean atmospheric conditions. The results also indicated that urban environmental conditions usually considered good for air quality, under the criteria of low mass concentration, do not properly serve as air quality standard to very small particles. In the size range of ultrafine particles, this traditional clean atmospheric condition can offer a strong risk to pulmonary hazards, since the cleansing of the atmosphere creates good conditions to increase the concentration of nucleation mode particles.
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Affiliation(s)
- Leila Droprinchinski Martins
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Jorge A. Martins
- Department of Environmental Engineering, Federal University of Technology, Londrina, 86020-430 Paraná Brazil
| | - Edmilson D. Freitas
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Caroline R. Mazzoli
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Fabio Luiz T. Gonçalves
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Rita Y. Ynoue
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Ricardo Hallak
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Taciana Toledo A. Albuquerque
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
| | - Maria de Fatima Andrade
- Department of Atmospheric Sciences, Institute of Astronomy, Geophysics and Atmospheric Sciences, University of São Paulo, Rua do Matão, 1226, São Paulo, 05508-900 São Paulo Brazil
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