A nebuliser typically “atomises” a solution into a fine mist. Various models are available from a traditional jet nebuliser using compressed air to newer designs using ultrasonics and electronic control sensors. These generated aerosols are often a formulation of an active drug suspension. Test procedures should measure aerodynamic particle size distribution from the mouthpiece with a cascade impactor suited to determine total drug mass released from the aerosols, quantity per impactor stage, mass median aerodynamic diameter and geometric standard deviation. A collection chamber should be considered with suggested guidelines of not less than 0.5 liters and with an unobstructed path length of not less than 13 cm from the mouthpiece. Specified test applications and various systems described meet both the pharmaceutical industry and its legislators.