stratosphere vs ventilation

stratosphere

noun
  • The region of the uppermost atmosphere where temperature increases along with the altitude due to the absorption of solar ultraviolet radiation by ozone. The stratosphere extends from the tropopause (10–15 kilometers) to approximately 50 kilometers, where it is succeeded by the mesosphere. 

ventilation

noun
  • The bodily process of breathing; the inhalation of air to provide oxygen, and the exhalation of spent air to remove carbon dioxide. 

  • An exchange of views during a discussion. 

  • The mechanical system used to assist breathing. 

  • The replacement of stale or noxious air with fresh. 

  • The public exposure of an issue or topic. 

  • The mechanical system used to circulate and replace air. 

How often have the words stratosphere and ventilation occurred in a corpus of books? (source: Google Ngram Viewer )