<p>The paper presents a mathematical modeling of the transport and deposition of solid particles in the human bronchial tree with a view to analyzing the influence of key factors of this deposition (density of particles, their size, the air flow velocity, and the geometry of the airways) on its efficiency for both man-made air pollutants (soot, cement dust) and for drugs. It is shown that a reduction in the air flow velocity contributes to increased particle deposition in the lower lobes of the lungs and that at intense inhalation (up to 76.2 L/min) over 50% of small particles settle in the alveolar zone, which is potentially dangerous for human respiratory health. It has been established that the density of particles has a significant effect on their deposition compared to the size of particles and the air flow velocity and that in the case of a “star-shaped” cross section of bronchi the deposition of particles in the lungs is more intense than in the case of a round-shaped section of bronchi due to a larger area of contact with the particles in the first case. The obtained results can be used to optimize inhalation systems of drug delivery and to assess risks connected with industrial particles′ effect on humans.</p>