Loud noise at work can damage hearing. Approximately 22 million U.S. workers are exposed to hazardous noise at work. To minimize occupational noise-induced hearing loss, the National Institute for Occupational Safety and Health (NIOSH) recommends that workers should not be exposed to noise at a level that amounts to more than 85 decibels (dBA) for 8 hours.
via NIOSH – Engineering Noise Control – Workplace Safety and Health Topic.