Migration and deposition characteristics of micro-dust in the human upper airway in dust-polluted tunnel environments.

Dust pollution in coal mine tunneling environment can cause serious hazards. This study presents a numerical analysis of the migration, deposition and escape characteristics of micro-dust in the human upper airway (HUA) under different labor intensities. The maximum deviation between simulation and experimental results was 8.97 %. The findings reveal that the expiratory flow was affected by the secondary motion, and two secondary vortices were formed around the posterior pharyngeal wall, which was prone to dust deposition. As the expiratory intensity increased, a large amount of 1-15 μm small-sized dust was deposited in the pharynx, and the deposition fraction (DFd) of 15 μm dust increased the most, reaching 77.13 %; 20-80 μm large-sized dust was difficult to exhale, and most were deposited near the nasal turbinate and nasopharynx. With the increase of density, the escape rate (ERd) of 1-15 μm dust showed a decreasing trend. The deposition of large-sized dust over 20 μm in nasopharyngeal region was more affected by density changes, but this fluctuation was reduced with increasing particle size. The study will help assess the human health risks of dust environment, develop more effective dust monitoring and control technologies and strategies for a cleaner, safer working air environment.