Predicted deposition of diesel particles in young humans

Abstract

This study utilized a mathematical model to predict the deposition patterns of inhaled diesel automobile exhaust particles in the respiratory tracts of young humans. A particle model was proposed to describe the physical characteristics and dynamic behavior of diesel particles, and this model was incorporated into the derivation of mathematical expressions for the airway deposition efficiency. An anatomical lung model for humans from birth to adulthood was formulated mathematically from available physiologic data and morphometric measurements. The growing lung model, together with the corresponding ventilation conditions, were then used to calculate the deposition of diesel particles in the lungs at any age up to maturity. We found that the deposition of diesel particles in young humans exhibited distribution patterns similar to those of adults. With the exception of alveolar deposition in very young children (below the age of 2 years), the predicted regional deposition fractions were always higher than in adults. For an equal duration of exposure, the surface minute dose in unciliated airways was predicted to change profoundly with age. The maximum calculated dose, which occurred at the age of 2 years, was approximately twice the adult value.