Using the 3 dB exchange rate principle for occupational noise exposure, if the permissible exposure at 85 dB(A) is 8 hours per day, the maximum permitted daily exposure at 91 dB(A) is:
- A 1 hour
- B 2 hours ✓
- C 4 hours
- D 6 hours
Correct answer: B. 2 hours
Explanation
Under the 3 dB exchange rate, every 3 dB increase in sound level halves the permissible exposure duration because perceived loudness roughly doubles the acoustic energy. From 85 dB (8 hours): 88 dB allows 4 hours, and 91 dB allows 2 hours. Option C corresponds to 88 dB, the intermediate step, and option A would apply at 97 dB. This principle underpins hearing conservation programmes in noisy industries.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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