What is the maximum work time allowed for a noise level of 99 dBA without noise protection?

What is the maximum work time allowed for a noise level of 99 dBA without noise protection?

• A. 10 minutes
• B. 15 minutes
• C. 30 minutes
• D. 19 minutes

Answer: (D)

Noise exposure limits are tied to a standard that describes how allowable time changes as the sound level increases. With the common NIOSH recommended exposure limit, the baseline is 85 dBA for 8 hours, and the rule (exchange rate) is 3 dB — every 3 dB increase cuts the permissible time in half. For 99 dBA, the level is 14 dB above 85 dBA. That’s about 14/3 ≈ 4.67 steps of halving. Start with 8 hours and divide by 2^4.67. 2^4.67 is roughly 25, so 8 hours / 25 ≈ 0.315 hours, which is about 19 minutes. So, the maximum work time without noise protection at 99 dBA is about 19 minutes under the typical 3 dB exchange standard. (Note: different standards, like OSHA’s 5 dB exchange, would give a longer allowable time.)

Noise exposure limits are tied to a standard that describes how allowable time changes as the sound level increases. With the common NIOSH recommended exposure limit, the baseline is 85 dBA for 8 hours, and the rule (exchange rate) is 3 dB — every 3 dB increase cuts the permissible time in half.

For 99 dBA, the level is 14 dB above 85 dBA. That’s about 14/3 ≈ 4.67 steps of halving. Start with 8 hours and divide by 2^4.67. 2^4.67 is roughly 25, so 8 hours / 25 ≈ 0.315 hours, which is about 19 minutes.

So, the maximum work time without noise protection at 99 dBA is about 19 minutes under the typical 3 dB exchange standard. (Note: different standards, like OSHA’s 5 dB exchange, would give a longer allowable time.)