Indoor particle inhalability of a stationary and moving manikin

Understanding particle inhalation caused by human activity is vital for developing estimates of inhalation exposure in indoor environments. This study used Computational Fluid Dynamics to compare nasal aspiration efficiency of a stationary manikin in uniform airflow and a moving manikin in stagnant air. The model was a full-scale body with detailed facial features at the nose. The stationary manikin case adopted a constant freestream velocities of 0.2 m/s and 0.4 m/s representing typical office wind environments; while the moving manikin case considered a walking speed of 0.4 m/s as a comparison case, followed with additional higher walking speeds (0.8 m/s and 1.6 m/s) to investigate realistic walking scenarios. Inhalation rates through the nose included light and medium breathing at 15 and 27 L per minute. The aspiration efficiency (AE) was used to quantify the nasal particle inhalability from an upstream release source. In order to evaluate the inhalability for the moving manikin, a 3-dimensional particle source was created and validated with a 2-dimensional particle source, which was common in studies for stationary manikins. Discrepancies in aspiration efficiencies were quantified between using 2- and 3-dimensional particle sources. The particle inhalability for a moving manikin was estimated for three particle sizes and three walking speeds. The inhalability of a walking manikin was found higher than a stationary manikin facing the wind, less relevant to particle sizes but more related to walking speeds. This study quantified the particle inhalability for moving manikins to characterise a more comprehensive scenario for modelling human respiration and developing estimations of particle exposure.