Simulation of aerosol dynamics and deposition of combustible and electronic cigarette aerosols in the human respiratory tract

The Aerosol Dynamics in Containments (ADiC) model describes the dynamic changes of inhaled cigarette smoke droplets during puffing, mouth-hold, and inspiration and expiration, considering coagulation, phase transition, conductive heat and diffusive/convective vapor transport, and dilution/mixing. The ADiC model has been implemented into a single path representation of the stochastic lung dosimetry model IDEAL to compute particulate phase deposition as well as vapor phase deposition in the airway generations of the human lung. In the present study, the ADiC model has been applied to the inhalation of combustible and electronic cigarette aerosols. Aerosol dynamics processes significantly influence the physical properties of particle and vapor phase in the human respiratory tract: (i) number reduction of inhaled aerosol particles is caused primarily by coagulation and less by deposition for both aerosols; (ii) hygroscopic growth rates are higher for e-cigarettes than for combustible cigarettes; (iii) the effect of particle growth on deposition leads to a lower total deposition in the case of cigarette smoke particles and a higher total deposition in the case of e-cigarette droplets relative to their initial size distributions; and, (iv) most of the nicotine is deposited by the vapor phase for both aerosols.