Every time you breathe, air travels down the trachea, through a series of channels, and then reaches little clusters of air sacs in the lungs. These tiny sacs facilitate a crucial exchange: allowing oxygen from the air we breathe into the bloodstream and clearing out carbon dioxide. Pneumonia wreaks havoc on this exchange system. Eve Gaus and Vanessa Ruiz detail how pneumonia attacks the lungs. [Directed by Artrake Studio, narrated by Alexandra Panzer].