Radon gas may be present in homes, particularly basements. Special kits should be used to determine its presence. This statement describes radon as:

Radon gas may be present in homes, particularly basements. Special kits should be used to determine its presence. This statement describes radon as:

• A. Presents a danger when undetected
• B. Is present in doses proportional to other sources
• C. Is entirely human-made
• D. Is the source of 100% of annual background dose

Answer: (A)

Radon is a naturally occurring radioactive gas that can seep into homes, especially basements. Because it has no smell, taste, or color, testing with special kits is the only reliable way to know whether it’s present. The health risk comes from long-term exposure to radon, which increases the chance of lung cancer, so it’s dangerous when it goes undetected in an enclosed living space. The statement is best understood as highlighting that the hazard depends on detection—without testing, people may unknowingly be exposed for years. Radon is not entirely human-made; it arises from uranium decay in the soil, and it does contribute to the overall background radiation, but it is not the sole source and not the entirety of the annual background dose.

Radon is a naturally occurring radioactive gas that can seep into homes, especially basements. Because it has no smell, taste, or color, testing with special kits is the only reliable way to know whether it’s present. The health risk comes from long-term exposure to radon, which increases the chance of lung cancer, so it’s dangerous when it goes undetected in an enclosed living space. The statement is best understood as highlighting that the hazard depends on detection—without testing, people may unknowingly be exposed for years. Radon is not entirely human-made; it arises from uranium decay in the soil, and it does contribute to the overall background radiation, but it is not the sole source and not the entirety of the annual background dose.