An epidemiologist reviewing lung cancer cases finds a cluster among never-smokers living in homes built over granite bedrock. Which indoor air pollutant is the most likely explanation?

• A Formaldehyde from pressed wood furniture
• B Asbestos fibres from ceiling insulation
• C Carbon monoxide from an attached garage
• D Radon gas seeping from the ground ✓

Explanation

Radon, a radioactive inert gas arising from uranium-238 decay in soil and rock such as granite, accumulates in poorly ventilated dwellings and is the second leading cause of lung cancer overall and the leading cause among non-smokers according to WHO. Formaldehyde causes nasopharyngeal irritation and cancer risk but not a lung cancer cluster pattern; asbestos relates mainly to mesothelioma and asbestosis; carbon monoxide causes acute toxic effects rather than malignancy.

Reference: Park's Textbook of Preventive and Social Medicine, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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