MEASUREMENT OF TOTAL LUNG DEPOSITION OF INHALED ULTRAFINE PARTICLES IN HEALTHY MEN AND WOMEN

Abstract

Ultrafine particles (< 0.10 µm in diameter) are present in great number in polluted urban air, thus posing a potential health risk. In this study, the total deposition fraction (TDF) of ultrafine aerosols with a narrow size distribution (number median diameter NMD = 0.04-0.1 µm and geometric standard deviation sigma_g = ~1.3) was measured in a group of young healthy adults (11 men and 11 women). TDF was obtained with 6 different breathing patterns: tidal volume (V_t) of 500 ml at respiratory flow rates (Q) of 150 and 250 ml/s; V_t = 750 ml at Q of 250 and 375 ml/s; and V_t = 1 L at Q of 250 and 500 ml/s. Aerosols were monitored continuously by a modified condensation nuclei counter while subjects were inhaling them with prescribed breathing patterns. For a given breathing pattern, TDF increased as particle size decreased, regardless of the breathing pattern used. For example, with V_t