Breathing volume and deposition in the respiratory tract.

The functional parameters influence the ventilation of the airways and determine the amount of aerosol penetrating there and the speed of airflow. 100 observations were made, on ten healthy subjects (5 men, 5 women) and with two breathing patterns (tidal volume 500 ml, respiration rate 16 min-1, and tidal volume 2000 ml, respiration rate 8 min-1). Inhaled and exhaled air were sampled by a Royco 518 sampler and the number, concentrations and particle size distributions in five particle size ranges were determined. In all the measurements the fraction deposited was higher in higher tidal volumes, especially in the class of the size range 0.5-1.75 microns. For tidal volumes of 2000 ml the deposited fraction for the women was greater than that for the men.