Experimental and numerical smoke carcinogen deposition in a multi-generation human replica tracheobronchial model

A better understanding of submicron particle deposition in the respiratory tract is needed to study the health effects caused by carcinogenic particles. Recent studies indicate that random diffusion is not sufficient to describe the motion of these particles in complex geometries, rendering conventional models inaccurate. A solid replica of excised human lung segments was used to create digital and hollow models of the tracheobronchial region to investigate deposition of mainstream (MS) and sidestream (SS) cigarette smoke particles. Particle sizes for the carcinogen Benzo(a)pyrene (BaP) in SS smoke, and total particulate matter (UVPM) in SS and MS smoke were measured and used to compare the simulation to experimental data. Excellent agreement was found between predicted and measured results. Random diffusion was not found to be significant for submicron particles indicating that particles were instead transported to the airway wall by convective diffusion. BaP in SS smoke was an average 0.3 mu m compared to 0.36 mu m for UVPM in SS smoke. The trends in both experimental and numerical results indicated that the BaP in SS smoke deposits at a slightly higher efficiency than the UVPM, indicating that carcinogen-specific deposition, rather than total particulate matter should be considered when investigating health effects.