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 annually and many employers lack current monitoring data that accurately characterizes job classification exposures.
Assessment Objectives
The assessment goal is to determine which job classifications reach the 85 dBA action level (requiring full HCP enrollment), which reach the 90 dBA PEL (requiring documented engineering controls assessment), and which fall below the action level. It is better to monitor and confirm a classification is sub-action-level than to assume it without data.
Instrument Selection and Configuration
| Instrument | Standard | Best For | OSHA Settings |
|---|---|---|---|
| Personal noise dosimeter | ANSI S1.25-1991 | Mobile workers; variable tasks | 5 dB XR, 90 dBA criterion, 80 dBA threshold, A-wt, Slow |
| Type 1/2 sound level meter | ANSI S1.4-1983 | Area surveys; noise source ID | A-weighting, Slow response |
| Integrating SLM | ANSI S1.4-1983 | Fixed workstations; area TWA | A-weighting; output Leq/TWA |
Representative Sampling Design
Sample all job classifications where exposure may reach the action level. For each classification, measure a sufficient number of workers to represent the range of tasks and conditions. For highly variable jobs (maintenance, material handling, mobile workers), full-shift dosimetry on multiple representative days is more reliable than short-duration samples. Document which workers were monitored, the date, and production conditions.
Action Thresholds and Required Response
| Result | Required Action |
|---|---|
| TWA below 85 dBA | No HCP required; retain records demonstrating sub-action-level exposure |
| TWA at or above 85 dBA action level | Enroll all affected workers in full 6-element HCP |
| TWA at or above 90 dBA PEL | HCP plus documented assessment of feasible engineering controls |
Documentation Requirements and Retention
OSHA requires noise monitoring records for 2 years minimum. Records must include: monitoring date, area or individual monitored, instrument type and serial number, pre/post calibration records, and results by worker or classification. Best practice: retain noise monitoring records indefinitely. A survey from 2010 showing job classification TWAs is relevant to a WC claim filed in 2035. See: OSHA noise monitoring requirements: complete guide.
Re-Monitoring Triggers
Operational changes that require re-monitoring: new equipment installation, increased production rates (more cycles per shift), equipment aging that raises noise levels, building changes that alter noise propagation, and STS clusters that suggest actual exposures may exceed the last survey's findings. An STS cluster in a job classification that was previously borderline at 87 dBA TWA is a signal to re-monitor before the next annual survey.
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