A factory chimney releases sulphur dioxide and particulate matter. During a temperature inversion episode, photochemical smog forms when SO₂ reacts with sunlight and atmospheric oxygen. The primary secondary pollutant responsible for the characteristic oxidant smog is:
- A Ozone (O₃) ✓
- B Carbon monoxide
- C Sulphur trioxide (SO₃)
- D Nitrogen gas (N₂)
Correct answer: A. Ozone (O₃)
Explanation
Photochemical (Los Angeles-type) smog involves NO₂ photolysis by UV light, releasing atomic oxygen that reacts with O₂ to form ozone (O₃). Ozone is the primary oxidant in photochemical smog and causes respiratory irritation, eye irritation, and pulmonary damage. SO₂ primarily causes London-type (reducing) smog in combination with fog and particulates. Carbon monoxide inhibits haemoglobin without contributing to photochemical oxidant formation. SO₃ forms sulphuric acid mist (acid rain).
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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