Quantitative deposition of ultrafine stable particles in the human respiratory tract

Theoretical models of particle deposition in the respiratory tract predict high fractional deposition for particles of less than 0.1 micron, but there are few confirming experimental data for those predictions. We have measured the deposition fraction of a nonhygroscopic aerosol in the human respiratory tract. The aerosol had a count mean diameter of 0.044 micron SD of 1.93, as measured with an electrical aerosol analyzer, and was produced from a 0.01% solution of bis(2-ethylhexyl) sebacate using a condensation generator. Subjects inhaled the aerosol using a controlled respiratory pattern of 1 liter tidal volume, 12/min. Deposition was calculated as the difference in concentration between inhaled and exhaled aerosol of five size fractions corrected for system deposition and dead-space constants. Three deposition studies were done on each of five normal male volunteers. Means (+/- SE) for the five size fractions were 0.024 micron, 0.71 +/- 0.06; 0.043 micron, 0.62 +/- 0.06; 0.075 micron, 0.53 +/- 0.05; 0.13 micron, 0.44 +/- 0.04; and 0.24 micron, 0.37 +/- 0.06. These data demonstrate that deposition of inhaled particles in the 0.024- to 0.24-micron size range is high and increases with decreasing size. These observations agree with and validate predictions of mathematical models.

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Numerical assessment of natural respiration and particles deposition in the computed tomography scan airway with a glomus tumour

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/09544089211024063 ◽

2021 ◽

pp. 095440892110240

Author(s):

Digamber Singh

Keyword(s):

Computed Tomography ◽

Respiratory Tract ◽

Particle Deposition ◽

Flow Characteristics ◽

Glomus Tumour ◽

Computed Tomography Scan ◽

Human Respiratory Tract ◽

Airflow Pattern ◽

Human Airways ◽

Tomography Scan

The human respiratory tract has a complex airflow pattern. If any obstruction is present in the airways, it will change the airflow pattern and deposit particles inside the airways. This is the concern of breath quality (inspired air), and it is decreasing due to the unplanned production of material goods. This is a primary cause of respiratory illness (asthma, cancer, etc.). Therefore, it is important to identify the flow characteristics in the human airways and airways with a glomus tumour with particle deposition. A numerical diagnosis is presented with an asymmetric unsteady-state light breathing condition (10 l/min). An in vitro human respiratory tract model has been reconstructed using computed tomography scan techniques and an artificial glomus tumour developed 2 cm above a carina on the posterior wall of the trachea. The transient flow characteristics are numerically simulated with a realizable (low Reynolds number) k–ɛ turbulence model. The flow disturbance is captured around the tumour, which influenced the upstream and downstream of the flow. The flow velocity pattern, wall shear stress and probable area of inflammation (hotspot) due to suspended particle deposition are determined, which may assist doctors more effectively in aerosol therapy and prosthetics of human airways illness.

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Sampling Conventions for Estimating Ultrafine and Fine Aerosol Particle Deposition in the Human Respiratory Tract

The Annals of Occupational Hygiene ◽

10.1093/annhyg/mer037 ◽

2011 ◽

Cited By ~ 16

Keyword(s):

Respiratory Tract ◽

Aerosol Particle ◽

Particle Deposition ◽

Human Respiratory Tract ◽

Fine Aerosol

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A theory of aerosol deposition in the human respiratory tract

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.1.77 ◽

1975 ◽

Vol 38 (1) ◽

pp. 77-85 ◽

Cited By ~ 116

Author(s):

D. B. Taulbee ◽

C. P. Yu

Keyword(s):

Particle Size ◽

Respiratory Tract ◽

Particle Deposition ◽

Particle Concentration ◽

Diffusion Mechanism ◽

Aerosol Deposition ◽

Lung Model ◽

Brownian Diffusion ◽

Human Respiratory Tract ◽

Apparent Diffusion

The deposition of inhaled aerosol particles in the human respiratory tract is due to the mechanisms of inertia impaction, Brownian diffusion, and gravitational settling. A theory is developed to predict the particle deposition and its distribution in human respiratory tract for any breathing condition. A convection-diffusion equation for the particle concentration with a loss term is used to describe the transport and deposition of particles. In this equation, an apparent diffusion coefficient due to the velocity dispersion in the lung is present and found to be the dominant diffusion mechanism for the cases considered here. Expressions for deposition by various mechanisms are also derived. The governing equation is solved numerically with Weibel's lung model A. The particle concentration at the mouth is calculated during washin and washout and compared favorably with experimental recordings for 0.5-mum diameter di(2-ethylhexyl) sebacate particles. The total deposition in the lung for particle size ranging from 0.05 to 5 mum is also computed for a 500-cm-3 tidal volume and 15 breaths/min. The results in general agree with recent measurements of Heyder et al. However, a particle size of minimum deposition is found to exist theoretically near 0.3 mum.

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Risk Assessment of Inhaled Particles Integrating Time-Activity Patterns with Respiratory Tract Particle Deposition Models

The Annals of Occupational Hygiene ◽

10.1093/annhyg/38.inhaled_particles_vii.973 ◽

1994 ◽

Keyword(s):

Risk Assessment ◽

Respiratory Tract ◽

Particle Deposition ◽

Activity Patterns ◽

Time Activity ◽

Inhaled Particles ◽

Deposition Models

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Prediction of Aerosol Deposition in the Human Respiratory Tract via Computational Models: A Review with Recent Updates

Atmosphere ◽

10.3390/atmos11020137 ◽

2020 ◽

Vol 11 (2) ◽

pp. 137 ◽

Cited By ~ 3

Author(s):

Vu Khac Hoang Bui ◽

Ju-Young Moon ◽

Minhe Chae ◽

Duckshin Park ◽

Young-Chul Lee

Keyword(s):

Respiratory Tract ◽

Particle Deposition ◽

Computational Models ◽

Aerosol Particles ◽

Three Dimensional ◽

Aerosol Deposition ◽

Research Area ◽

Human Respiratory Tract

The measurement of deposited aerosol particles in the respiratory tract via in vivo and in vitro approaches is difficult due to those approaches’ many limitations. In order to overcome these obstacles, different computational models have been developed to predict the deposition of aerosol particles inside the lung. Recently, some remarkable models have been developed based on conventional semi-empirical models, one-dimensional whole-lung models, three-dimensional computational fluid dynamics models, and artificial neural networks for the prediction of aerosol-particle deposition with a high accuracy relative to experimental data. However, these models still have some disadvantages that should be overcome shortly. In this paper, we take a closer look at the current research trends as well as the future directions of this research area.

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