Decibel Ratings and Hazardous Time Exposures of Common Noises
| EXAMPLE |
DECIBEL LEVEL |
DANGEROUS TIME EXPOSURE |
| Quiet library, soft whisper |
30 dB(A) |
All Exposure is safe |
| Quiet office, living room |
40 dB(A) |
All Exposure is safe |
| Light traffic, gentle breeze, refrigerator |
50 dB(A) |
All Exposure is safe |
| Normal conversation, Air Conditioner at 20ft, sewing machine |
60 dB(A) |
All Exposure is safe |
Busy traffic, noisy restaurant.
At this level, noise may begin to affect hearing if constantly exposed |
70 dB(A) |
Risk begins with unprotected exposure |
Truck traffic, lawnmower, shop tools.
As loudness increases the safe time exposure decreases. |
90 dB(A) |
Unprotected exposure should be limited to less than 8 hours |
Chainsaw, boiler shop, pneumatic drill.
Exposure may be dangerous at 100 dB(A). Safe exposure is cut in half with each 5 dB increase. |
100 dB(A) |
Unprotected exposure should be limited to less than 2 hours |
| Rock Concert in front of speakers, sandblasting, thunderclap. Exposure can injure the ear. |
120 dB(A) |
Unprotected exposure is considered seriously dangerous |
Gunshot, jet plane at 50 ft.
Noise at this level may cause actual ear pain. |
140 dB(A) |
Any unprotected exposure can cause damage |
Decibels (dB) are measured logarithmically. An increase of 10 dB is ten times as loud.
E.g. 80 dB is 10X louder than 70 dB; 90 dB is 100X louder than 70 dB.
SOURCE: The Canadian Society of Otolaryngology