The 'killer fog' episode of London in December 1952, which caused several thousand excess deaths within days, was due primarily to which combination?

• A Nitrogen oxides and ozone under intense sunlight
• B Carbon monoxide alone from vehicular exhaust
• C Sulphur dioxide and particulate matter under temperature inversion ✓
• D Hydrogen sulphide from marshy land near the Thames

Explanation

The London smog was a classical reducing smog produced by coal combustion releasing sulphur dioxide and smoke particles, trapped by a winter temperature inversion over the city. Excess deaths occurred mainly from bronchitis, pneumonia and cardiac disease in the elderly. Option A describes photochemical smog of the Los Angeles type, which requires sunlight and vehicles rather than coal smoke and inversion.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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