<prompt> In living rooms, number of air changes in one hour should be: March 20132-Jan3-Feb4-Mar5-Apr  <response>: Ans. B i.e. 2-3 Air changes per hour is a measure of how many times the air within a defined space normally a room or house is replaced. It is recommended that in the living rooms, there should be 2 or 3 air changes per hour; in work rooms and assemblies 4 to 6 air changes. 