The deposition model makes use of experimental regional deposition data to determine the filtering efficiencies of respective regions. Since the experimental data used have been obtained at a simple breathing pattern, there is only one possibly erroneous 'model' influencing the results of this evaluation. Moreover, from the efficiencies obtained, conclusions can be drawn about the areas which had served as input to the model. The efficiencies are expressed as semi-empirical functions of the breathing parameters, thus inter- and extrapolating the experimental data. In a second step, these 'generalized' efficiencies are used to re-calculate regional deposition for a wide range of particle sizes and breathing parameters. Given reliable regional deposition input data, this model is believed to yield quite reliable information about particle deposition in the human airways.