What is the maximum permissible exposure to noise in the mine?

What is the maximum permissible exposure to noise in the mine?

• A. 115 dBA
• B. 110 dBA
• C. 120 dBA
• D. 100 dBA

Answer: (A)

Noise exposure is managed using time-weighted averages, with a baseline limit of 90 dBA over an 8-hour shift. When the noise level increases, the allowed exposure time decreases in steps. Using a common 5 dB exchange rate, each 5 dB increase halves the permissible exposure time: 95 dBA allows about 4 hours, 100 dBA about 2 hours, 105 dBA about 1 hour, 110 dBA about 30 minutes, and 115 dBA about 15 minutes. So the maximum permissible exposure at 115 dBA is roughly 15 minutes; beyond that, protective measures or shorter exposure is required. This is why 115 dBA is the best answer.

Noise exposure is managed using time-weighted averages, with a baseline limit of 90 dBA over an 8-hour shift. When the noise level increases, the allowed exposure time decreases in steps. Using a common 5 dB exchange rate, each 5 dB increase halves the permissible exposure time: 95 dBA allows about 4 hours, 100 dBA about 2 hours, 105 dBA about 1 hour, 110 dBA about 30 minutes, and 115 dBA about 15 minutes. So the maximum permissible exposure at 115 dBA is roughly 15 minutes; beyond that, protective measures or shorter exposure is required. This is why 115 dBA is the best answer.