An Inhalation System for Characterizing Total Lung Deposition of Ultrafine Particles

A new inhalation system is described for characterizing total lung deposition of ultrafine aerosols in humans as a function of particle diameter and breathing pattern. An electrostatic aerosol classifier generated the aerosols and an aerosol electrometer measured their concentrations in inhaled and exhaled air. An inductive plethysmograph measured tidal volumes and was part of a visual feedback system that assured breathing patterns were standardized. A fast-switching solenoid valve system separated inhaled and exhaled air and managed air flow patterns throughout the system. A hygroscopic aerosol, sodium chloride, was used for characterization, but the system is readily adaptable to an insoluble aerosol. The calibration of the system, methods used for data acquisition and analysis, and some of the system's advantages and limitations are discussed. Examples of data are shown to illustrate the system's capability to measure total lung deposition of ultrafine particles.