In-Vivo Measurements of Micrometer-Sized Particle Deposition in the Nasal Cavities of Taiwanese Adults.

It has been observed that Asians and Caucasians possess considerably different craniofacial features, which may affect the anatomical structure of the upper respiratory tract and, consequently, the characteristics of particle deposition. Most deposition studies on the human respiratory tract were primarily based on a limited number of Caucasian subjects. Therefore, data of the particle deposition efficiency in the upper respiratory tract of Asians are needed to supplement the understanding of the deposition characteristics in the human respiratory tract. This study measured the nasal deposition efficiency of particles ranging from 0.5 to 20 μm in five Taiwanese male and four Taiwanese female adults under different inspiratory flow rates. The measured deposition efficiency showed a very large intersubject variability in the inertial parameters, ranging between 103 to 5 × 104 μm2 cm3/s, and the deposition efficiency of the subjects with similar values of the minimum nasal cross-sectional area approaches to each other. This study showed that Taiwanese adults have lower nasal deposition efficiency than Caucasians, and that the differences in the nostril shape, inclination of nostrils, and nasal hair density between the two ethnic groups are likely the causes. In addition, this study suggested that up to 15% of overestimation in the nasal deposition efficiency for larger particles may occur if the inhalation efficiency is not considered. An empirical equation adopting inspiratory flow rate and the minimum nasal cross-sectional area was developed to predict the nasal particle deposition in the upper airway of Taiwanese adults. Copyright 2012 American Association for Aerosol Research [ABSTRACT FROM PUBLISHER]