Which areas are prohibited from being used as return air sources?

The correct answer identifies areas that typically have high levels of moisture, pollutants, or contaminants, making them unsuitable for return air sources. Using air from spaces such as bathrooms, toilet rooms, and kitchens can lead to the circulation of odors, humidity, and harmful particles through the HVAC system. This can compromise indoor air quality, which is essential for the health and comfort of the building occupants.

Bathrooms and toilet rooms often contain a high concentration of moisture, which can lead to mold and mildew growth if this air is recirculated in the home. Kitchens, similarly, may contain cooking fumes, grease particles, and other volatile organic compounds that are undesirable in the conditioned air.

In contrast, the other areas listed in the other choices may not attract the same level of concern regarding contamination. For instance, while garages and utility rooms might also pose some risks, the choices specifically pinpointing areas tied directly to personal hygiene and food preparation align more closely with prohibitions set forth in the International Mechanical Code. This regulation aims to ensure that the air circulated within the living environment remains clean and does not reintroduce harmful contaminants.