An epidemiological study links indoor air pollution in homes built over granite-rich terrain with bronchogenic carcinoma among non-smokers. The most likely causative agent is:

• A Radon gas seeping from soil and rock ✓
• B Formaldehyde from pressed wood furniture
• C Carbon monoxide from biomass fuel combustion
• D Asbestos fibres from roof insulation

Explanation

Radon is a colourless, odourless radioactive gas formed by decay of uranium-238 present in granite soils and rocks. It accumulates in poorly ventilated basements and ground-floor rooms, and its alpha-emitting daughters irradiate bronchial epithelium. After smoking, radon is the second leading cause of lung cancer worldwide. Granite terrain, as in parts of Kerala and Karnataka, raises indoor radon levels substantially above outdoor concentrations.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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