Which factor most strongly influences indoor radon concentration in homes?

Which factor most strongly influences indoor radon concentration in homes?

• A. Humidity levels
• B. Ventilation rate
• C. Cracks in the foundation
• D. Indoor ozone concentration

Answer: (C)

Radon is a gas that comes from the decay of uranium in soil, and the amount that accumulates indoors is set mainly by how easily soil gas can enter the building. Cracks in the foundation provide the primary entry points, so they largely determine indoor radon levels. Even if a home has different humidity, indoor ozone, or varying ventilation, the gas must first get inside through those openings; sealing cracks dramatically reduces the inflow and lowers concentrations. Ventilation affects how much radon is diluted, but it’s the presence of cracks that sets how much radon can accumulate in the first place.

Radon is a gas that comes from the decay of uranium in soil, and the amount that accumulates indoors is set mainly by how easily soil gas can enter the building. Cracks in the foundation provide the primary entry points, so they largely determine indoor radon levels. Even if a home has different humidity, indoor ozone, or varying ventilation, the gas must first get inside through those openings; sealing cracks dramatically reduces the inflow and lowers concentrations. Ventilation affects how much radon is diluted, but it’s the presence of cracks that sets how much radon can accumulate in the first place.