How many hours per day can you be exposed to a noise level of 100 dB?

• A. 2 hours
• B. 1 hour
• C. 4 hours
• D. 8 hours

Answer: (A)

Understanding how long you can be exposed to a given noise level relies on the exposure standard that ties decibels to allowable time. Under OSHA’s typical framework, a noise level of 90 dB for 8 hours is the baseline. The standard uses a 5 dB exchange rate, so for every 5 dB increase, the permissible exposure time halves. That means 95 dB allows 4 hours, and 100 dB allows 2 hours. So at 100 dB, the maximum unprotected exposure is 2 hours per day. The other options correspond to different levels (e.g., 95 dB for 4 hours, 105 dB for 1 hour, 90 dB for 8 hours). If hearing protection or controls reduce the actual exposure, longer times could be tolerated, but without protection the limit at 100 dB is 2 hours.