The Respiratory Tract Deposition Model Proposed by the ICRP Task Group

• Published in: Radiation protection dosimetry 1991-01, Vol.38 (1-3), p.159-165
• Main Authors: James, A.C., Stahlhofen, W., Rudolf, G., Egan, M.J., Nixon, W., Gehr, P., Briant, J.K.
• Format: Article
• Language: English
• ISSN: 0144-8420; 1742-3406
• DOI: 10.1093/oxfordjournals.rpd.a081085

The Task Group has developed a new model of the deposition of inhaled aerosols in each anatomical region of the respiratory tract. The model is used to evaluate the fraction of airborne activity that is deposited in respiratory regions having distinct retention characteristics and clearance pathways, and/or tissue sensitivity: the anterior nares and the extrathoracic airways of the naso-and oropharynx and larynx, the bronchi, the bronchioles, and the alveolated airways of the lung. Drawn from experimental data on total regional deposition in human subjects, the model is based on extrapolation of these data by means of a detailed theoretical model of aerosol transport and deposition within the lung. The Task Group model applies to all practical conditions, and for aerosol particles and vapours from atomic size up to very coarse aerosols with an activity median aerodynamic diameter of 100 µm. The model is designed to predict regional deposition in different subjects, including adults of either sex, children of various ages, and infants, and also to account for anatomical differences among Caucasian and non-Caucasian subjects. The Task Group model represents aerosol inhalability and regional deposition in different subjects by algebraic expressions of aerosol size, breathing rates, standard lung volumes, and scaling factors for airway dimensions. It is emphasised that the current version of the model described here is still provisional.