Assessing human health risks: impact of variable air quality index on asymmetric spirometry flow

The escalation of occupational and environmental pollutants poses a significant threat to human health, particularly exacerbating chronic respiratory diseases (CRD). Globally, CRD account for 4.0 million reported deaths (Momtazmanesh et al. EClinicalMedicine 59, 2023). This study investigates the repercussions of exposure to unfavourable Air Quality Index (AQI) levels on respiratory health, focusing on asymmetric spirometry flow during natural inspiration at a flow rate of Qin = 10 l/min. Here, employing digital imaging techniques, we developed an in-silico human respiratory tract model, encompassing up to the 7th bifurcation of a healthy male individual. The results reveal that the dynamics of inspired airflow and particles, particularly in turbulent regions, influence particle deposition in the airways. Thus, the upper airways and bifurcations region have higher deposition efficiency of fine particles ~ 2.5 and 10 μm, consequently creating hotspots for respiratory illnesses. Moreover, to quantify the internal flow characteristics, we utilised a set turbulence model, and the trajectory of fine particles was computed by discrete phase model (DPM). The localised quantitative quantification of particle physics focuses on deposition efficiency at different time instants, t = 1.5 s, 2.1s and 2.5 s, complemented by insights into internal flow features, particles are depicted and quantified through regional deposition efficiency, while flow physics is presented by, surface streamlines, turbulent kinetic energy, turbulence intensity and Q-criterion. These findings have a significant implication in effective diagnosis and management of chronic respiratory diseases (CRD), providing valuable insights into the intricate interplay between air quality, airflow dynamics, and respiratory health.