The development of theoretical models and the experimental studies that have been done describe the deposition of aerosols in the respiratory tract as a function of particle size and respiration patterns. Descriptions of the anatomical structure of the respiratory tract, air flows, and the physical behavior of airborne particles illustrate the basis of the various models of inhaled particle deposition. Particle density, shape, hygroscopicity, and pathology influence particle deposition, and the particle size distribution and deposition site of the inhaled aerosol influence the resultant biological response.
Stuart BO. Deposition of Inhaled Aerosols. Arch Intern Med. 1973;131(1):60-73. doi:10.1001/archinte.1973.00320070056006