After smoking, this is the second leading cause of lung cancer. A naturally occurring gas that forms in rocks, soil, and water:

Radon disclosure is crucial in real estate practice because it represents a significant health hazard that agents must be prepared to address with clients. This question tests your knowledge of environmental hazards that require disclosure in California. The core concept is identifying naturally occurring substances that pose health risks. To arrive at the correct answer, you must recognize that radon is a radioactive gas that forms from the decay of uranium in soil, rock, and water. While smoking is the leading cause of lung cancer, radon is the second leading cause and is particularly dangerous in enclosed spaces like homes. This question is challenging because it requires knowledge of environmental hazards beyond the more commonly discussed issues like lead paint or carbon monoxide. Understanding radon connects to broader real estate knowledge about material fact disclosure and environmental hazards that affect property value and occupant health.