Deposition of man-made fibers in a human nasal airway

Many occupational lung diseases are associated with exposure to aerosolized fibers in the workplace. The nasal airway is a critical route for fiber aerosol to enter the human respiratory tract. The fiber deposition efficiency in the nasal airway could be used as an index to indicate the fraction of the inhaled fibers potentially transported to the lower airways. In this research, experiments of fiber deposition in the human nasal airway were conducted. Man-made carbon, glass, and titanium dioxide fibers in the inertia regime were used as the test fiber materials. The deposition studies were carried out by delivering aerosolized fibers into a human nasal airway replica at constant human inspiratory flow rates ranging from 15 l/min to 43.5 l/min. The deposition results were compared in detail between these fiber materials to study how the fiber characteristics affected the nasal airway deposition. The results showed that the deposition efficiency of the carbon fiber increases as the fiber impaction parameter increases. Many carbon fibers deposited in the anterior region of the nasal airway. In contrast, very few glass or titanium dioxide fibers deposited in the nasal airway, but relatively more of these two fibers deposited in the turbinate region. This result implies that, if a fiber in the inertia regime is inhaled during normal human breathing, the smaller the fiber, the more easily it could enter the human lower respiratory tract, possibly causing harm to the human respiratory tract.