Transport and deposition of inhaled man-made vitreous and asbestos fibers in realistic human respiratory tract models: An in silico study

Particles longer than 5 μm and with a length/diameter ratio >3 are defined as fibers. Asbestos or other fibers are still identified in residential environments due to the emission from asbestos-used building materials. The respiratory system is the primary route of asbestos exposure; under a longer residence time, asbestos-related adverse health effects are inevitable. Currently, asbestos fibers have been replaced with man-made vitreous fibers (MMVFs); however, studies have revealed some similar biological effects of MMVFs with asbestos. Therefore, MMVFs-induced diseases need to be determined by analyzing their deposition characteristics and foci in human respiratory tracts. In this study, we used computational fluid dynamics method to investigate fibers' airflow and deposition patterns in two realistic human respiratory models. Two drag models were used to predict the deposition of uniform 1 μm (asbestos) and 3.66 μm (carbon fiber-CF) diameter, 15–300 μm long fibers. Two drag models provided comparable results with the experimental data. Comparatively, asbestos deposition was independent of fiber length, while CF deposition increased proportionally to fiber length. The highest level of local deposition was detected in the anterior nasal cavity. The results obtained from this study can extend current knowledge of human vitreous fiber exposure-related lung diseases.