Numerical Investigation of Aerosol Deposition in Lung Airways During Inhalation and Exhalation

Abstract

Continuous deposition of workplace pollutant particles on lung airways during respiratory actions seriously threatens the lung health of persons performing tasks in polluted environments. While inhalation-deposition relationships have been explored, the impact of exhalation on the deposition of polydisperse particles remains unclear. This study aims to analyze the exhalation-driven deposition of fine and coarse occupational pollutant particles in polydisperse form, considering varying levels of physical activity. Computer simulations are conducted on the airway section G3-G4 to study the patterns of airflow dynamics and deposition of grain dust, coal fly ash, and bituminous coal particles across a spectrum of activity intensities, utilizing idealized and realistic lung models. Key findings include the observation of early emergence of secondary flows in the real model compared to the idealized model, a notable shift in deposition patterns towards the postbifurcation zones, and the influence of physical activity intensity on particle deposition. Additionally, deposition primarily occurs near the cranial ridge during inhalation, while exhalation leads to deposition in pre- and postbifurcation zones. The effect of gravity on deposition is more pronounced at lower flow rates but diminishes at higher flow rates. PM2.5 deposition isxv minimal and random in the idealized model but becomes more significant and consistent in the real model, with substantial deposition rates observed for PM10 particles. This research underscores the increased risk of lung diseases for workers in polluted environments during vigorous activity.