Which statement best describes a hazard associated with pressure-induced backdrafting?

• A. It ensures a steady supply of fresh outdoor air
• B. It reduces energy consumption by ventilation
• C. It lowers indoor humidity
• D. It can cause combustion gases to enter the living space

Answer: (D)

Pressure-induced backdrafting creates a pressure difference that can reverse the flow in vents, pulling combustion gases back into the living space instead of venting them outside. The key hazard is that dangerous gases, especially carbon monoxide, can accumulate indoors, posing serious health risks or even life-threatening exposure. The other statements describe beneficial or unrelated effects, not the danger posed by backdrafting. So the core hazard described is combustion gases entering the living space, which is why that option is the best description. To reduce risk, ensure proper venting and make-up air, use appropriately vented appliances, and install CO detectors.