Mining employers face a distinct hearing conservation regulatory framework under MSHA 30 CFR Part 62, which differs meaningfully from OSHA 29 CFR 1910.95. The differences in action level, audiometric testing scope, and program requirements mean that a program compliant with one standard is not automatically compliant with the other. According to CDC/NIOSH, approximately 22 million U.S. workers face hazardous occupational noise, and mining workers have among the highest occupational NIHL rates in the country.
Side-by-Side: MSHA 30 CFR Part 62 vs OSHA 1910.95
| Requirement | OSHA 1910.95 | MSHA 30 CFR Part 62 |
|---|---|---|
| Action Level | 85 dBA TWA — triggers full HCP | 90 dBA TWA — triggers hearing loss prevention program |
| Permissible Exposure Level | 90 dBA TWA (8 hr) | 90 dBA TWA (same PEL) |
| Exchange rate | 5 dB | 5 dB (same as OSHA) |
| Audiometric testing scope | Only workers at or above 85 dBA action level | ALL miners must receive baseline audiogram; ongoing testing for exposed miners |
| Baseline timing | Within 6 months of first exposure above action level | Within 12 months of starting work at a mine |
| Annual audiogram | Within 12 months of last audiogram (enrolled workers) | Within 12 months for miners exposed at or above 90 dBA action level |
| STS definition | 10 dB avg shift at 2000, 3000, 4000 Hz vs baseline | Same as OSHA; MSHA uses "significant threshold shift" terminology |
| HPD requirement | Available at 85 dBA; mandatory above 90 dBA PEL or after STS | Required at or above 90 dBA action level |
| Covers | General industry, construction; NOT mining operations | All MSHA-regulated mines (coal and metal/nonmetal, underground and surface) |
The Most Important Difference: Universal Audiometric Testing Under MSHA
MSHA 30 CFR Part 62 requires baseline audiometric testing for ALL miners within 12 months of starting at a mine — regardless of their specific noise exposure level. This is significantly broader than OSHA 1910.95, which only requires audiometric testing for workers confirmed at or above 85 dBA TWA. Under MSHA, a miner working in a quiet office area within a mine property must still receive a baseline audiogram. This universal audiometric requirement creates a comprehensive audiometric record for all mining employees from hire, which also provides the strongest possible WC defense foundation.
Jurisdictional Boundary: Which Standard Applies Where
The MSHA/OSHA jurisdictional boundary is operation-specific, not site-specific. At a surface mine or quarry:
- Mining and extraction operations — MSHA jurisdiction (30 CFR Part 62)
- Processing plant operations that are not directly part of the mining extraction process — may fall under OSHA 1910.95
- Office, warehouse, and support facilities on mine property — OSHA jurisdiction in many cases
Employers with operations straddling the MSHA/OSHA boundary must maintain separate, compliant programs for each regulatory framework. See: OSHA vs MSHA hearing conservation: full comparison.
STS Follow-Up Under MSHA
MSHA's significant threshold shift notification and follow-up requirements parallel OSHA's in most respects. When an STS is identified, the miner must be notified in writing and offered the opportunity to be examined by a licensed physician or audiologist. The mining operator must take corrective action including re-evaluation of HPD adequacy. MSHA inspectors check STS follow-up records as a standard component of hearing conservation inspections.
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