Effect of particle mass size distribution on the deposition of aerosols in the human respiratory system

Elemental mass size distributions were experimentally determined in atmospheric aerosols collected at four different locations in Budapest, Hungary, comprising a urban background site, two downtown sites and a road tunnel. Based on these distributions, deposition fractions for the various elements in the respiratory system were calculated for a healthy Caucasian adult male, female and 5-year-old child under sitting breathing conditions by a stochastic lung deposition model. The highest deposition values were observed in the extrathoracic region regardless of subject's age and gender, and chemical species and size distributions. Deposition in the tracheobronchial tree and acinar region was much smaller than that in the extrathoracic region. Variations in the deposition fractions due to differences in the size distributions were really significant only in the extrathoracic region. Surprisingly, the different size distributions yielded similar depositions in the thoracic region for a given gender as far as the shape of the deposition curve and the total amount are concerned. Regional deposition fractions were compared for the male, female and child, and for various size distributions (sampling location) and elements.