What is the role of humidity in IAQ according to 62.1?

• A. Humidity has no impact on IAQ according to 62.1.
• B. Humidity affects contaminant growth and occupant comfort; 62.1 focuses on IAQ while comfort ranges are addressed by ASHRAE 55.
• C. Humidity is the primary focus of 62.1, more than IAQ.
• D. Humidity control is prohibited in most spaces to save energy.

Answer: (B)

Humidity matters for IAQ because moisture levels influence the growth of biological contaminants like mold and dust mites, as well as odor and the release of chemicals from building materials. It also affects how comfortable occupants feel, which is an aspect of perceived air quality. ASHRAE 62.1 focuses on achieving acceptable IAQ through ventilation, filtration, and moisture management, but it does not set the comfort humidity ranges—that is done by ASHRAE 55. So humidity is relevant to IAQ in 62.1, while the specific comfort ranges for humidity come from ASHRAE 55.