Background: The risk of secondary inhalation of medical aerosols has been highlighted as a significant risk factor for both caregivers and bystanders in both the clinical and homecare settings. The level of fugitive emissions released by varying nebuliser types used is poorly understood. The aim of this study was to investigate the potential for inhalation of secondary aerosols from two commercially available nebuliser/mouthpiece combinations while also commentating on Aerosol Delivery Performance. Methods: A 2.5 mL dose of Salbutamol (1 mg/mL) was nebulised as a tracer aerosol using two commercially available nebuliser types, i.e. Vibrating mesh (VMN) (Aerogen Ultra, Aerogen, Ireland) and Jet (JN) (Cirrus 2, Intersurgical, United Kingdom). The nebuliser was connected to a breathing simulator (Ingmar ASL 5000) via an absolute filter (RespirGard II 303, Baxter, Ireland) (BPM 15, Vt 500 mL, I:E 1:1). Mass concentrations and size distributions were recorded during nebulisation using two Aerodynamic Particle Sizer9s (APS) (APS, model 3321 TSI Inc., St. Paul, MN) at 0.8m and 2.2m from the nebuliser. Conclusions: Based on these findings, the JN emits higher exhaled aerosol mass concentrations to the atmosphere at both distances from the nebuliser. The VMN emits lower exhaled aerosol mass concentrations and concurrently delivers a larger inhaled dose to the intended patient.