[Theoretical calculations of the deposition of non-spherical particles in the upper airways of the human lung]

In the contribution presented here a computer model for the description of non-spherical particle deposition in the upper human respiratory tract is introduced. The theoretical approach is mainly based on the principle of the aerodynamic diameter, whose calculation was carried out according to most current scientific findings. With the help of this parameter deposition patterns for various particle categories (fibers and oblate disks) and breathing conditions (sitting, light-work and hard-work breathing) were simulated. Concerning cylindrical fibers with a diameteror = 1 microm, an increase of the aspect ratio beta (i.e. particle length/particle diameter) causes a significant enhancement of deposition in the uppermost regions of the respiratory tract (oropharynx, larynx, trachea). This effect is additionally intensified by an increase of the inhalative flow. Regarding the oblate disks with a diameteror = 1 microm, any decrease of the aspect ratio leads to an enhancement of deposition in the deeper lung regions, representing an effect contrary to that observed for fibers. An increase of the inhalative flow only induces a limited decrease of the effect.