Abstract

Particulate matter is an important class of air pollutants to which humans are exposed. This report addresses the possibilities of mathematical models to analyze differences in dosimetry between healthy persons and those with obstructive pulmonary diseases. The main aim of the study was to evaluate existing PM transport/deposition models with respect to their conceptual and practical merits, in order to find an optimal model to estimate deposition of PM in the human airways. We used the ICRP model for preliminary calculations of PM deposition in the human airways for 6 monodisperse aerosols, with different single aerodynamic particle diameters. Subjects of different age and gender, at various levels of ventilation activity, and with or without obstructive pulmonary disease were evaluated. The results show that: (i) the burden in adult males with pulmonary disease is 4-5 times higher than in their healthy equivalents, (ii) the burden in children is 1.1-2.5 times higher than in an adult male, (iii) heavy exercise at high ventilation rates results in a 1.4-2.0 higher burden than at light exercise, (iv) resting and sleeping involve much lower burdens: 0.2-0.4 times the burden under light exercise. The observed variations are mainly related to differences in ventilation rates and effective lung area between the subjects. The main recommendations for further research at the National Institute of Public Health and the Environment in the field of deposition modeling include (i) the development and application of a dynamic process model for detailed study of deposition in the airways of humans and laboratory animals, in order to make an inter-species comparison and to support experimental work with laboratory animals, and (ii) a survey on the variability in the physiological airway parameters in the human population, to enable estimates of actual exposure of the whole population to particulate matter to support risk assessments.