What 29 CFR 1910.95 requires (plain English)
29 CFR 1910.95 protects general-industry workers from occupational noise: one of the most common workplace hazards and a cause of permanent, incurable hearing loss. Because noise-induced hearing loss develops gradually and painlessly, workers often do not notice it until it is severe, which is why the standard mandates both exposure limits and an ongoing hearing conservation program to catch damage early. It sets a permissible exposure limit of 90 dBA as an 8-hour time-weighted average, using a 5-decibel exchange rate.
The standard is built on two thresholds. The permissible exposure limit (PEL) is 90 dBA over 8 hours; the 5-dB exchange rate means the allowable time halves for each 5-dB increase (4 hours at 95 dBA, 2 hours at 100 dBA, and so on). The action level is 85 dBA over 8 hours: a lower threshold that triggers the hearing conservation program even though it is not itself a violation. When employee exposures equal or exceed the 85 dBA action level, the employer must implement monitoring, provide hearing protection, and enroll workers in audiometric testing.
The hearing conservation program has defined elements: exposure monitoring, baseline and annual audiograms to detect a standard threshold shift, hearing protectors made available (and required above the PEL or after a threshold shift), employee training, and recordkeeping. When feasible engineering or administrative controls can reduce exposures, they must be used before relying on hearing protection. NIOSH recommends a more protective 85 dBA exposure limit with a 3-dB exchange rate; many employers adopt those criteria as best practice even though OSHA's enforceable limit remains 90 dBA with a 5-dB exchange.