| Because of equipment limitations, researchers have largely used monodisperse aerosols to investigate the deposition of particles in the human lung. The lack of polydisperse aerosol deposition data has lead to the use of a series of monodisperse aerosols to predict polydisperse deposition. This work focused on modeling polydisperse aerosol deposition and developing a method to directly measure polydisperse aerosol deposition in the human lung. This direct measurement method was used to determine the reasonability of using a series of monodisperse aerosols to simulate polydisperse aerosol deposition.;A mathematical model was used explore the effect of particle density and size distribution on particle deposition. It was found that particles with high density and small geometric diameter had slightly greater deposition fractions than particles that were aerodynamically similar, but had lower density and larger geometric size. Also, polydisperse aerosols containing a significant proportion of submicron particles deposited in the pulmonary airways with greater efficiency than aerodynamically similar aerosols comprised of geometrically larger porous particles. The same model, along with basic deposition equations was used to explore the effects of slip, shape and density on aerosol behavior. It was found that particle characteristics dictate aerodynamic properties and can be manipulated to achieve optimal particle behavior.;A polydisperse aerosol inhalation system was developed, built and validated. This system was used, with a packed bed as a surrogate to the human lung, to investigate monodisperse and polydisperse aerosol deposition. There was no difference in deposition between discrete sections of polydisperse and monodisperse aerosols when the polydisperse aerosol was conditioned with a charge neutralizer. Without conditioning, discrete sections of polydisperse aerosols with diameters less than, or equal to 1 mum, deposited more than monodisperse aerosols. This finding indicates the importance of conditioning aerosol with a charge neutralizer after the nebulization of a sebacate/alcohol solution, as well as the reasonability of using a series of monodisperse aerosols to simulate polydisperse aerosol deposition under simple conditions. However, relative to existing monodisperse systems, the new aerosol inhalation system's ability to use polydisperse aerosols may provide a significant advantage to researchers by reducing human study duration and subject exposure. |
