A fundamental study of the primary atomisation mechanism and aerosol plume development of the pressurised metered dose inhaler MyattBen 2017 The pressurised metered dose inhaler (pMDI) is the most popular device for delivery of inhaled therapeutic aerosols to the lungs for treatment of asthma and COPD. One significant weakness of the pMDI is the high level of oropharyngeal deposition leading to low drug delivery efficiency. With the increasing prevalence of respiratory diseases and desire to improve the efficacy of drug delivery a deeper fundamental understanding of the atomisation process and aerosol plume physics is required. This thesis reports the findings of experimental studies using optical diagnostic techniques to investigate the internal flow processes and to characterise the spray plume of pharmaceutically relevant formulations. A new experimental protocol for laboratory measurements of pMDIs has been developed. [Continues.]