What is the formula to calculate the number of air changes (N)?

The formula to calculate the number of air changes per hour (N) is based on the relationship between the air flow rate and the volume of the space being ventilated. This is expressed as N = Q x 60 / V, where:

• N represents the number of air changes per hour,

• Q indicates the air flow rate (usually in cubic meters per second or cubic feet per minute),

• V is the volume of the space being ventilated (in cubic meters or cubic feet).

By multiplying Q by 60, the formula converts the air flow rate into an hourly figure, thus providing the number of times the air in a given volume is exchanged over the course of one hour. This is a crucial aspect of understanding ventilation effectiveness in maintaining air quality for occupational health and safety.

In this context, the other choices do not accurately reflect the relationship needed to quantify air changes effectively. Calculating N requires considering the flow rate as a rate per hour and relating it to the volume of the space, which is accomplished through the formula mentioned above.