On the deposition of unipolarly charged particles in the human respiratory tract

The effect of unipolar electrostatic charges on the total deposition efficiency in the human respiratory tract has been investigated. Monodisperse carnauba wax particles of diameter between 0.3 and 1.1 micron were charged, in a corona discharge apparatus, with a number of elementary charges ranging from about 30 to 110 per particle, with a narrow distribution. The experiments were performed with volunteers breathing through the mouth at 12 resp/min at constant flow rate, without pauses. The increase in deposition was of the order of 15 to 30% relative to neutral but otherwise unchanged monodisperse aerosol. The increase depended on the charges carried by each particle, but was independent of the concentration. Therefore it may be concluded that the variation can be ascribed to the effect of electrostatic attraction between the particle charge and the image charge on the airway wall.