Figure 4: The influence of ethanol cosolvent concentrations on the aerodynamic particle size characteristics of HFA 227 formulations as quantified using a Next Generation Impactor. Surfactant concentrations were kept constant (data represent mean ± SD, ). MOC: microorifice collector. * (ANOVA/Tukey’s) 15% w/w EtOH versus 10 and 5% w/w EtOH and ** comparing all formulations.