What must be kept at least 10 feet away from any operable openings or air intake?

The requirement for subslab soil exhaust ducts to be kept at least 10 feet away from any operable openings or air intake is based on safety and air quality considerations. These ducts are designed to expel gases and vapors that may accumulate beneath a building, particularly in instances where soil contamination is present. If located too close to operable openings or air intakes, there is the potential for harmful substances to be drawn back inside the building, compromising indoor air quality and potentially posing health risks to occupants.

Maintaining this distance ensures that any exhaust does not interfere with the ventilation system or create pathways for unwanted pollutants to enter habitable spaces. This guideline is essential for the protection of public health and safety, aligning with established building codes that prioritize safe and effective indoor environments.

The other options, while important for their respective functions and safety considerations, do not have the same stringent requirements regarding their proximity to openings or intakes. This specificity is what makes the requirement for subslab soil exhaust ducts particularly important in maintaining safe and healthy indoor air conditions.