OSHA 1910.95(d) requires noise monitoring when information indicates any employee may be exposed at or above 85 dBA. According to CDC/NIOSH, approximately 22 million U.S. workers face hazardous noise, and many employers lack current noise monitoring that accurately characterizes job classification exposures.
Step 1: Define the Scope
Identify all areas and job classifications where exposure may reach the action level. Start broad — any area with significant machinery, compressed air, impact operations, or high-speed equipment warrants inclusion. It is better to monitor and confirm sub-action-level exposure than to assume it without data.
Step 2: Select Instruments
Personal noise dosimeters (ANSI S1.25-compliant) for mobile workers with variable tasks — these measure cumulative dose over the full shift. Sound level meters (ANSI S1.4-compliant) for fixed workstations or area surveys. Configure dosimeters for OSHA settings: 5 dB exchange rate, 90 dBA criterion, 80 dBA threshold, A-weighting, slow response. Calibrate before and after each use; document calibration results.
Step 3: Conduct Representative Sampling
For each job classification: sample a sufficient number of workers across the range of tasks, production rates, and equipment conditions typical for that classification. For highly variable jobs, full-shift dosimetry on multiple representative days is more reliable than short-duration samples. Document which workers were monitored, the date, and production conditions during monitoring.
| Result | Action Required |
|---|---|
| TWA <85 dBA (all job classes) | No HCP required; retain records showing sub-action-level |
| TWA ≥85 dBA (any job class) | Enroll affected workers in full 6-element HCP |
| TWA ≥90 dBA (any job class) | HCP required + documented engineering controls assessment |
Step 4: Document and Retain
OSHA requires noise monitoring records for 2 years. Include: monitoring date, area/individual monitored, instrument type and serial number, calibration records for that date, and results. Best practice: retain indefinitely — monitoring records from 2010 may be relevant to WC claims filed in 2035. See: OSHA noise monitoring requirements: complete guide.
Step 5: Re-Monitor When Conditions Change
Re-monitoring triggers: new equipment, changed production rates, equipment aging, building reconfiguration, or an STS cluster suggesting actual exposures are higher than last monitoring showed. Calendar-based re-monitoring (every X years) without a change trigger is not required but is reasonable practice for facilities with dynamic operations.
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