Influence of Particle Size upon the Retention of Particulate Matter in the Human Lung.

Measurement and calculation of deposition of china dust in various portions of respiratory tract by exhalation partitioning (measured by CO/sub 2/ content) are discussed. Data on retention of various sized dusts in upper respiratory or alveolar regions were converted to percent deposition curves. Upper respiratory deposition decreased from approx. 75% at 5 ..mu..m to approx. 10% at 1.5 ..mu..m. Alveolar deposition peaked (approx. 55%) at 1 ..mu..m.