Definitions of ventilation:

• noun:   the act of supplying fresh air and getting rid of foul air
• noun:   a mechanical system in a building that provides fresh air

  Example: "She was continually adjusting the ventilation"

• noun:   free and open discussion of (or debate on) some question of public interest
• noun:   the bodily process of inhalation and exhalation; the process of taking in oxygen from inhaled air and releasing carbon dioxide by exhalation