Prolonged exposure to noise levels greater than the following can impair hearing permanently -
Repeated or continuous exposure to the noise around 100 decibels may result in a permanent hearing loss; inner ear damage may vary from minor changes in the hair cells to complete destruction of the organ of Coi. Park's Textbook of Preventive and Social Medicine, 22nd edition, Page No. 689
40 decibels
85 decibels
100 decibels
140 decibels
Environment and health