Inhalability of micro-particles through the human nose breathing at high free-stream airflow velocities

Abstract

In this study, the inhalability of microparticles through a human nasal passage under various ambient airflow conditions is calculated. As megacities are becoming polluted and being exposed to the polluted windy outdoor environments is inevitable nowadays, from the toxicological point of view, it would be wise to investigate the impact of air pollution on human health. Though, as few studies have attempted to address this concern, especially for high free-stream velocities comprehensively, the main emphasis was placed on assessing the impact of both inhalation and Total Deposition Fraction (TDF) of particles. Several free stream airflow velocities from 1 to 70 km/h are simulated to cover almost all stormy outdoor conditions that could typically happen. RANS models and stochastic models for turbulent particle dispersion were examined to simulate the particle motions properly in such turbulent conditions. The impact of high ambient airflow velocities on the aspiration efficiency and the TDF of micro-particles were assessed for a wide range of particle sizes. The results reveal that TDF of the integrated airway is mostly higher than that of the detached airway system due to the non-uniformity of both airflow field and particle distribution which happens at the nostrils, similar to the work of Naseri et al. (Anderson and Anthony, 2013) [24]. Yet, contrary to that study in which the flow field was laminar, and there were no notable differences between the TDF of these two cases at different breathing flow rates, the differences become more notable when the breathing regime becomes fully turbulent.