Evaluating the effects of breathing zone and anatomical completeness on respiratory particle inhalation and deposition in human respiratory tract.

Authors

Jie Li, Xueren Li, Jiaqi Fan, Ziqi Chen, Yidan Shang, Xiaochuan Li, Xiang Fang, Liang Yuan, Bingyou Jiang, Xinjian He, Jiyuan Tu

Published in

Environmental pollution (Barking, Essex : 1987). Pages 128807. Jul 25, 2026. Epub Jul 25, 2026.

Abstract

As the interface between environmental exposure and respiratory intake, the breathing zone is often simplified in respiratory CFD models, while the broader influence of model completeness on airflow and particle deposition remains insufficiently quantified. In this study, a comprehensive human respiratory model (hereinafter referred to as the "all-in-one model") encompassing the upper and lower respiratory tracts and the throat region was initially constructed and integrated with a spherical breathing zone. The effect of the breathing zone was evaluated by developing six computational models with varying anatomical completeness. Three particle release approaches were implemented, including nostril inlet release, volumetric release within the breathing zone, and surface-based release on the breathing zone boundary. The Eulerian-Lagrangian approach was adopted, and total and regional particle deposition patterns were carefully analysed. The results revealed that the breathing zone, together with varying anatomical completeness, significantly alters airflow development in the nasal vestibule, valve region, and posterior turbinate zones, with sectional peak velocities reduced by up to 12%. While total nasal deposition for 10μm particles varies moderately (14.55%-45.55%), substantial regional discrepancies are observed, with nasal vestibule deposition differing by up to 14-fold between models with and without the breathing zone. Particle release strategy further influences deposition predictions, as nostril inlet release produces 956%-1345% higher vestibule deposition compared with breathing-zone-based release. These findings demonstrate that neglecting the breathing zone and adopting simplified particle release strategies can substantially degrade assessment accuracy. Incorporating physically consistent breathing zone representations is essential for improving the accuracy and reliability of CFD-based respiratory exposure assessments.

PMID:
42501911
Bibliographic data and abstract were imported from PubMed on 26 Jul 2026.

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