Under ILO conventions, 'Noise-Induced Hearing Loss' (NIHL) is an occupational disease when cumulative noise exposure exceeds:
- A 85 dB(A) 8-hour time-weighted average (TWA) for ≥5 years ✓
- B 90 dB(A) peak level for ≥1 year
- C 80 dB(A) TWA for ≥2 years
- D 75 dB(A) for any duration in hazardous process industry
Correct answer: A. 85 dB(A) 8-hour time-weighted average (TWA) for ≥5 years
Explanation
The internationally accepted occupational noise exposure action level is 85 dB(A) as an 8-hour time-weighted average (TWA). In India, the Factories Act specifies 90 dB(A) as the permissible exposure limit, but the NIHL compensable threshold under occupational disease schedules is 85 dB(A) for prolonged exposure (≥5 years). NIHL is characteristically sensorineural, bilateral, and most severe at 4000 Hz (the C5 dip), distinguishing it from presbycusis. Mandatory audiometric surveillance is required above the action level.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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