Deposition of Cigarette Smoke Particles in the Human Respiratory Tract

Abstract

Understanding tobacco related cancer etiology requires the knowledge of cigarette smoke particle (CSP) deposition. Measurements of CSP deposition are inconsistent with typical deposition data. A deposition model that accounts for hygroscopic growth, coagulation, particle charge, and cloud behavior of CSP has not yet been presented. Nor have smoking patterns been accounted for in either deposition measurements or computer models. The dosimetry of Benzo[a]pyrene (BaP), which would add critical information to the relationship between anatomic site preferences of tumors and their histology, is currently unknown.The deposition model presented in this study is the rst to accurately account for the dynamic behavior of CSP. Using the model results, the effects of each dynamic behavior on deposition is examined along with the effect of smoking patterns. The dosimetry of BaP is also calculated. The results indicate that coagulation, hygroscopicity, and particle charge increase the total deposition by 16% over the stable charge-neutral case, which predicts 46%. Cloud behavior increases total deposition ef ciency by 36% over the simple case. Increasing exhalation time increases the deposition fraction by 3.9%/s. BaP concentrations are found to be as large as 1.8E-4 ng/cm 2 for the cloud model and 2.4E-5 ng/cm 2 for single particle behavior. Mass deposition occurs preferentially in the pulmonary region for all cases. However, signi cant increases in the tracheobronchial region are found if cloud behavior is considered. The model results indicate that cloud behavior, and not particle charge, coagulation, and hygroscopic growth, has a predominant effect on deposition. More data is required on cloud behavior in the airways to improve the accuracy of the model.

A scattering methodology for droplet sizing of e-cigarette aerosols

“…One important aspect to consider is the physical properties of inhalable aerosols and the representative parameter obtained from measured size distributions. Depending on the size distribution of an aerosol, some of the inhaled dose is transported further to the tracheobronchial section or to the alveolar region of the ''lung'' (Bernstein, 2004;Kane et al, 2010;Robinson & Yu, 2001). Generally, a respirable aerosol (Hinds, 2012) has a related mass median aerodynamic diameter (MMAD) of less than 2.5 mm; at this size, more than 80% of the aerosol mass reaches the alveolar region.…”

The Relevance of Animal Models for Aerosol Studies

“…Most mathematical particle deposition models will consider the first three of these mechanisms, which are generally the dominant ones, and sophisticated models may include additional mechanisms. (31)(32)(33)(34)(35)(36) Several reference books provide pertinent basic information on properties of aerosol particles and their behavior. (37)(38)(39)(40) Traditional particle deposition models apply particle deposition mechanisms to simplified airway structures to predict deposition doses for the major regions of the respiratory tract.…”

Conditions for Cloud Settling and Rayleigh-Taylor Instability

“…These authors provide little guidance as to when cloud settling will occur beyond stating that when the ratio is much greater than unity cloud settling occurs and when it is much less than unity it does not. Stober et al (1978), Chen and Yeh (1990), Martonen (1992), Phalen et al (1994), and Robinson and Yu (2001) observed bulk motion of mainstream cigarette smoke in air. Martonen (1992) observed the path of mainstream smoke in human airway casts and concluded from theoretical analysis that cloud motion would occur when a 3 mm diameter cloud has a mass concentration much >52 mg/m 3 .…”