How many hours per day can you be exposed to a noise level of 105 dB?

How many hours per day can you be exposed to a noise level of 105 dB?

• A. 1 hour
• B. 2 hours
• C. 0.5 hours
• D. 4 hours

Answer: (A)

Exposure limits for noise are defined by how long you can be exposed to a given sound level without risking hearing damage. A common safety standard uses an exchange rate: for every 5 dB increase in noise level, the allowable exposure time is cut in half. When you start from 90 dB allowed for 8 hours, increasing by 5 dB to 95 dB reduces the time to 4 hours, another 5 dB to 100 dB reduces it to 2 hours, and another 5 dB to 105 dB reduces it to 1 hour. So, at 105 dB, the maximum safe exposure time per day is about one hour. If you were using a stricter 3 dB exchange rate, the allowable time would be much shorter (around 7–8 minutes at 105 dB), but the common construction standard uses the 5 dB rate, yielding one hour.

Exposure limits for noise are defined by how long you can be exposed to a given sound level without risking hearing damage. A common safety standard uses an exchange rate: for every 5 dB increase in noise level, the allowable exposure time is cut in half. When you start from 90 dB allowed for 8 hours, increasing by 5 dB to 95 dB reduces the time to 4 hours, another 5 dB to 100 dB reduces it to 2 hours, and another 5 dB to 105 dB reduces it to 1 hour. So, at 105 dB, the maximum safe exposure time per day is about one hour. If you were using a stricter 3 dB exchange rate, the allowable time would be much shorter (around 7–8 minutes at 105 dB), but the common construction standard uses the 5 dB rate, yielding one hour.