Occupational Noise Exposure (OSHA / NIOSH)

A defining detail is the exchange rate: the increase in level that halves the permitted exposure time. OSHA uses a 5 dB exchange rate while NIOSH recommends 3 dB, so the same noise environment can yield different calculated doses depending on which rule applies. The specific levels, action values, and exchange rates are given in the limit table on this page.

Any employer whose workers face sustained loud noise falls under these rules: manufacturing and heavy industry, construction, mining, agriculture, aviation ground operations, entertainment venues, and transport. Where exposures reach the action level, the employer must establish a hearing conservation program: monitoring, audiometric testing, hearing protection, training, and record-keeping. Safety managers and occupational-health teams are responsible for measuring exposures and demonstrating that they stay within the limits, since noise-induced hearing loss is one of the most common and entirely preventable occupational diseases.

Two complementary measurements establish compliance. Noise dosimetry places a small dosimeter on the worker to integrate sound energy across the whole shift, producing the time-weighted average and dose that are compared against the action level and permissible limit. Area sound-level measurements, taken with a sound level meter, map noise across a workplace to identify which machines and zones drive exposure and where controls or signage are needed. For defensible results the instrument should meet the relevant IEC 61672 class and be field-calibrated with an acoustic calibrator before use; peak and impulsive levels are captured alongside the TWA.