This document discusses pulmonary drug delivery systems (PDDS). It begins by defining PDDS as devices or formulations meant to deliver drugs into the body via the pulmonary route. Some key advantages of PDDS are localized drug deposition, avoidance of first-pass metabolism, and rapid onset of action. The document outlines applications of PDDS such as treating asthma, COPD, and insulin delivery. It also discusses the components of aerosols including propellants, containers, valves, and actuators. The manufacturing process and quality control tests for aerosols are described.