Exposure to polluted environments rich in inhalable aerosols: A study on transport and deposition patterns of aerosol particles in the human respiratory tract

Abstract

Exposure to air pollution environments rich in aerosol particles can cause serious damage to the human respiratory system. This study reconstructed a human respiratory tract model using medical CT scans. Six different respiratory patterns were obtained through ergonomic experiments. The study simulated and analyzed the transport and deposition patterns of dust under varying respiratory efforts and levels of environmental pollution. Experimental validation was conducted using a self-developed respiratory dust exposure system. The results indicate that inertial collision plays a significant role in the deposition mechanism as particles are transported through the human respiratory tract. The airflow forms a whirlpool at the throat, which contributes to dust deposition in this area. During exhalation, the airflow carries a large number of particles suspended in the respiratory tract from inhalation to be deposited in the upper respiratory tract. In the turbinate region, the concentration of dust is 74 % higher compared to inhalation. The curve representing the particle deposition rate with respiration effort can be approximated by the equation $Y=A\bullet X^B$. As respiration effort increases, particles are transported deeper into more distal bronchi and show a greater tendency to deposit on the anterior walls of the airways. Notably, larger particles show higher sensitivity to changes in respiration velocity. When the respiration effort increases from 10 L/min to 85 L/min, the average deposition efficiency of particles changes from 18.67 % to 37.48 %. Among these, the escape rate of 1 μm particles remains consistently between 96.9 % and 98.4 %.