Representative mass distributions for the Collison nebulizer and the FFAG at the points of generation and inhalation. ○, Collison nebulizer, preinhalation (MMAD of 3.84 μm, GSD of 2.12); •, Collison nebulizer, inhaled (MMAD of 2.51 μm, GSD of 1.28); ▪, FFAG, preinhalation and inhaled (MMAD of 12.63 μm, GSD of 1.35).