Regarding the relationship between ventilation rate and IAQ, which statement is true?

• A. IAQ is determined solely by outdoor air supply.
• B. IAQ depends only on occupant density.
• C. IAQ depends on both ventilation rates and contaminant control strategies.
• D. IAQ is unaffected by air distribution.

Answer: (D)

IAQ is shaped by how much outdoor air is used to dilute pollutants and by how well contaminants are controlled and removed in the space. Ventilation helps reduce concentrations by bringing in fresh air, but it only works effectively if internal sources are managed and filtration or cleaning devices are appropriate for the contaminants present. Air distribution matters because how air moves determines where contaminants accumulate or are removed; poor mixing or stratification can leave high concentrations in occupied zones even with decent ventilation. So the true statement is that IAQ depends on both ventilation rates and contaminant control strategies, with air distribution influencing the actual exposure.