. . "Abstract Drug delivery to the respiratory tract locally has become an increasingly effective and important therapeutic method for treating a variety of pulmonary disorders, including chronic abstractive disease, asthma, bronchitis, pneumonia, and cystic fibrosis. Increase in prevalence respiratory disorders is a major factor driving the growth of global respiratory inhaler devices market. The effectiveness of pharmaceutical aerosols therapeutic performance is affected by various factors such as type and characteristics of propellants, whose properties are vapor pressure of propellants, viscosity and density flash point and also other factors such as type and characteristics of active ingredients, containers, valves, and actuators, along with percentage of moisture content and mechanism of emitted dose deposition, spray pattern, efficiency of valve crimping, and measurement of particle size aerosols. The purpose of this book chapter is to discuss the in-process and finished product quality control tests for pharmaceutical aerosols based on pharmacopeia standards and specifications." .