At 100 decibels, hearing may be permanently damaged in less than two hours, and each 5-decibel increase cuts the safe exposure time in half. To put those figures in perspective here are some common noises and their decibel levels. Constant exposure should be limited to less than 8 hours. Constant exposure should be limited to less than 2 hours. More than 30 minutes may damage hearing.
Any exposure is dangerous.
Hearing loss is inevitable without ear protection. One in four people over the age of 65 suffers from hearing loss. One in three people over the age of 75 has trouble hearing. Most often, the damage is permanent and can be helped only through hearing aids. Left untreated, loss of hearing can affect mental and even physical health.