Effect of electrostatic charge on oral-extrathoracic deposition for uniformly charged monodisperse aerosols

• Examines the effect of induced charge on particle deposition in the mouth–throat.
• Uses monodisperse uniformly charged particles to study deposition quantitatively.
• Introduces a relation for predicting mouth–throat deposition for charged particles.

An in vitro study was conducted with the aim of investigating the effect of particle charge on deposition in the oral-extrathoracic airways of human adults. To generate monodisperse droplets with uniform charge, an atomizer was designed and built. The atomizer generates monodisperse droplets using controlled Rayleigh jet breakup and charges the droplets uniformly via electrostatic induction. Experiments were conducted at various aerodynamic particle diameters (3.3, 4.6 and 5.9 μm) and volume flow rates (15 and 30 L/min) for a wide range of charges per particle (0–25,000 elementary charges). The results show substantial increases in deposition due to induced charge electrostatics, especially for smaller particle sizes. A dimensionless empirical correlation was developed for predicting deposition in the mouth–throat region of human adults including induced charge electrostatic effects.