How many hours per day can you be exposed to a noise level of 115 dB?

How many hours per day can you be exposed to a noise level of 115 dB?

• A. Fifteen minutes
• B. One hour
• C. Two hours
• D. Thirty minutes

Answer: (A)

The key idea is how OSHA sets permissible noise exposure: for every 5 dB increase above the reference level, the allowable exposure time is cut in half. The reference is 90 dBA for an 8-hour day. Here, 115 dB is 25 dB above 90 dBA, which is five 5-dB steps. Halving five times: 8 hours → 4 → 2 → 1 → 0.5 → 0.25 hours. That equals 0.25 hours, or 15 minutes, of exposure per day. So the best answer is 15 minutes. If you needed more time, you’d have to lower the noise level or use hearing protection to bring effective exposure down.

The key idea is how OSHA sets permissible noise exposure: for every 5 dB increase above the reference level, the allowable exposure time is cut in half. The reference is 90 dBA for an 8-hour day. Here, 115 dB is 25 dB above 90 dBA, which is five 5-dB steps. Halving five times: 8 hours → 4 → 2 → 1 → 0.5 → 0.25 hours. That equals 0.25 hours, or 15 minutes, of exposure per day. So the best answer is 15 minutes. If you needed more time, you’d have to lower the noise level or use hearing protection to bring effective exposure down.