ASHRAE 62.1 Standards and Air Systems Practice Test

Occupant exposures refer to the actual dose occupants receive, meaning the concentration of contaminants in the breathing zone multiplied by the time they are exposed. In IAQ design we focus on what people truly inhale over their occupancy period, which emerges from how contaminants are generated, diluted, and removed by the system. The mass of contaminants generated by equipment is a source term—it tells you how much contaminant enters the space but not how much occupants actually experience. The rate of outdoor air changes per hour is a ventilation metric that affects dilution of contaminants, but it isn’t the exposure itself. The total number of occupants over a day influences potential exposure opportunities, but it doesn’t define the exposure concentration or duration.