Development of a Taiwanese head model for studying occupational particle exposure

This study reports a method for constructing a head model with a continuous airway passage beginning from the nostrils and continuing through the second generation of bronchi, using computerized tomographic (CT) images of facial features and airway passages from a healthy Taiwanese male adult. When combined with a manikin torso and connected to a cyclic breathing machine, the Taiwanese head model can simulate human breathing movement. This model enables investigation of important parameters of deposition efficiency without the inter- and intrasubject variability that often occurs in human studies. Being an assembly of numerous polymethyl methacrylate (PMMA) plastic slabs, the head model can be applied to study particle deposition at specified respiratory regions. The nasal geometry obtained in this study was compared with those obtained in other studies, which demonstrated this head model to be 36% smaller in nostril cross-sectional area than for European Americans. Additionally, this Taiwanese head model was found to be shorter in nasal cavity length, and the minimum cross-sectional area was only 50% compared to that of European Americans. This study also measured the nasal inhalation efficiency and deposition for particles ranging from 1.5 to 15 microm under various ventilation levels to test the feasibility of this head model. Future particle deposition studies using this Taiwanese head model can be compared with the currently available data, which are primarily based on Caucasian cast models or human subjects.