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Most occupational health professionals in the United States learn the OSHA framework: 29 CFR 1910.95, the 85 dBA action level, the 10 dB STS, the 21-day notification window. That framework governs general industry. It does not govern mining. The 5.5 million Americans who work in mining operations — coal, metal, nonmetal, sand, gravel, stone — are regulated by the Mine Safety and Health Administration under a completely separate statutory and regulatory system. MSHA’s noise standard, 30 CFR Part 62, was comprehensively revised in 2000 and applies uniformly to all mines. While Part 62 and 1910.95 share many structural features, the differences are consequential: a different threshold for the highest-severity hearing loss trigger, a mandatory dual hearing protection requirement with an explicit TWA threshold, a formal government reporting requirement when hearing loss is confirmed, and no written program requirement. This guide covers every material difference, so mine operators and safety managers know which framework applies and what it requires.
Soundtrace provides audiometric surveillance programs for mine operators under MSHA 30 CFR Part 62, including baseline and annual audiograms, PLHCP review, and reportable hearing loss documentation.
MSHA Part 62 and OSHA 1910.95 both require audiometric testing at the 85 dBA action level and share a 90 dBA PEL — but Part 62 has a 25 dB reportable hearing loss threshold (vs. OSHA’s 10 dB STS), a mandatory dual protection trigger at 105 dBA, and a requirement to report qualifying hearing loss to MSHA under Part 50. Mine operators who apply the OSHA framework to their mining operations are not compliant with the MSHA standard.
MSHA’s jurisdiction extends to all mines and mining operations under the Federal Mine Safety and Health Act of 1977 (Mine Act). A mine is broadly defined as any mining area, including open-cut mines, underground mines, quarries, strip mines, and associated surface facilities. MSHA jurisdiction covers coal mines, metal mines (gold, silver, copper, iron), nonmetal mines (stone, sand, gravel, clay, phosphate), and processing facilities directly associated with mining operations.
The critical boundary question for multi-operation employers: if a facility performs both mining operations and processing or manufacturing operations that are not directly associated with mining, the mining operations fall under MSHA while the manufacturing operations may fall under OSHA. A single employer may face compliance obligations under both agencies for different portions of their workforce. MSHA inspects frequently — all underground coal mines are inspected four times per year, surface coal mines twice, and metal/nonmetal mines at least once annually — making compliance failures highly visible.
MSHA Part 62 and OSHA 1910.95 share the same core noise exposure thresholds: an 85 dBA TWA action level triggering HCP enrollment, a 90 dBA TWA PEL, and a 5 dB exchange rate. These parallel numbers can mislead mine operators into assuming the two standards are functionally identical. They are not.
The similarities in thresholds reflect Part 62’s deliberate modeling after 1910.95 when MSHA revised its noise standard in 2000. MSHA explicitly acknowledged that mine operators with 1910.95-compliant programs would not need significant modification to meet most Part 62 requirements. But several substantive differences remain, and MSHA has its own inspection, citation, and penalty structure independent of OSHA. An MSHA inspector who identifies a hearing conservation deficiency will cite under 30 CFR Part 62, not 1910.95.
The most operationally significant difference between the two standards is the hearing loss detection threshold. Under OSHA, a 10 dB average shift at 2000/3000/4000 Hz from baseline is a Standard Threshold Shift requiring notification, HPD refitting, and potentially 300 Log recording. Under MSHA Part 62, the formal term for the most significant trigger is “reportable hearing loss” — an average change of 25 dB or more at those same frequencies.
This 2.5x threshold gap is consequential. A miner with a 15 dB average shift would trigger OSHA’s full STS response sequence in a general industry setting. In a mining operation under Part 62, a 15 dB shift does not reach the reportable hearing loss threshold. However, the mine operator is still expected to investigate, offer HPD refitting, and take steps to address the potential ongoing exposure risk — Part 62 simply does not call this an STS or require formal notification in the same way.
Part 62 does not have an explicit response protocol for shifts between 10 and 25 dB. Mine operators who apply only the 25 dB reportable threshold and ignore shifts in the 10–24 dB range are missing an early warning signal. Best practice is to apply a 10 dB investigation threshold internally — even though it is not formally required — to catch progressive hearing loss before it reaches the reportable level and generates a Part 50 filing obligation.
One of the most practically significant differences between Part 62 and 1910.95 is Part 62’s mandatory dual hearing protection requirement. Under 30 CFR 62.140, when a miner’s full-shift noise exposure equals or exceeds the dual hearing protection level — defined as 105 dBA TWA (equivalent to 800% of the permissible dose) — the mine operator must provide and ensure the concurrent use of both an earplug-type and an earmuff-type hearing protection device simultaneously.
This is not a recommendation. It is a mandatory requirement with specific HPD type requirements. The mine operator must supply both devices, ensure workers wear both, and document compliance. Single HPD use at 105 dBA TWA or above is a Part 62 violation.
Mining operations that reach 105 dBA TWA are not uncommon. Continuous miners, roof bolters, blasting operations, longwall shearers, and surface drilling equipment can produce sustained exposures at these levels. Mine operators should verify which equipment and operations exceed the 105 dBA threshold through dosimetry and maintain written documentation of dual protection requirements for affected job classifications.
One of the most operationally distinctive features of Part 62 is the requirement to file occupational illness reports with MSHA when reportable hearing loss is confirmed. Under 30 CFR Part 50, mine operators must report occupational illnesses — including noise-induced hearing loss meeting the 25 dB threshold — to MSHA within 10 working days of confirmation. This report is filed on MSHA Form 7000-1.
OSHA has no equivalent requirement. The OSHA 300 Log is an internal record retained at the worksite for employee and OSHA inspector review. MSHA’s Part 50 report goes directly to the agency, becomes part of the mine’s publicly accessible injury and illness record, and is used by MSHA for enforcement targeting, inspection planning, and national mining health surveillance. A mine with a pattern of Part 50 hearing loss filings is more likely to receive a targeted MSHA noise inspection.
Unlike OSHA 300 Log entries that sit in a file cabinet until an inspector arrives, Part 50 reports are filed with MSHA proactively. Mine operators who fail to file when required face separate civil penalties for the recordkeeping violation in addition to any underlying hearing conservation program citation. Maintaining an audiometric program that can identify reportable hearing loss promptly — and having a process for Part 50 filing — is operationally critical.
Part 62’s audiometric testing requirements mirror 1910.95 closely. Baseline audiograms must be obtained within 6 months of enrollment in the HCP (or within 12 months if a mobile test van is used). The 14-hour pre-test quiet period is required. Annual audiograms must be compared to baseline for hearing loss detection. The audiometric technician must be under the supervision of a physician or audiologist.
One Part 62-specific provision: the mine operator must notify the miner to avoid high noise levels for at least 14 hours immediately preceding the baseline audiogram, and may not expose the miner to workplace noise during the 14-hour quiet period. (HPD use may be substituted for the quiet period under certain conditions.) This is essentially the same as OSHA’s requirement but stated more explicitly. The medical privacy provision in Part 62 is also slightly different: when a miner is referred to a physician for evaluation, any results unrelated to occupational noise exposure must not be revealed to the mine operator without the miner’s written consent.
Part 62.180 requires training within 30 days of enrollment in the HCP and every 12 months thereafter. Required training content under Part 62 includes:
The mine operator must certify the date and type of training given each miner and maintain the miner’s most recent training certification for as long as the miner is enrolled in the HCP. This training certification record is distinct from OSHA’s training documentation requirements and is specifically tied to each enrolled miner rather than to a general program record.
Part 62.190 specifies recordkeeping requirements for mine operators enrolled in an HCP. Required records and retention periods include:
Under Part 62.190, miners and their designated representatives have the right to access their own audiometric records and noise monitoring data upon request. Mine operators must provide access within a reasonable time. This parallels OSHA’s employee access requirements but is explicitly codified in Part 62 rather than incorporated by reference from other standards.
Part 62 does not require mine operators to compile their hearing conservation activities into a single written program document. Each required element — monitoring, audiometry, HPDs, training, recordkeeping — is independently required, but there is no provision requiring a written HCP.
This differs from the general industry context, where OSHA’s 1910.95 implicitly requires that a “continuing, effective hearing conservation program” be administered, which in practice means documenting the program elements. Mine operators who rely on the absence of an explicit written program requirement are taking a practical risk: MSHA inspectors expect to see evidence of a functioning program. A written program is the most efficient way to demonstrate that all Part 62 elements are addressed and provide evidence of the program’s ongoing administration.
Part 62 permits age correction using the same framework as OSHA — Appendix tables (Tables 62-3 and 62-4 for males and females) allow mine operators to subtract expected age-related threshold change from measured shifts. Like OSHA, age correction under Part 62 is optional. When applied, it can reduce or eliminate the apparent shift, potentially removing a 25 dB reportable hearing loss finding. The decision to apply age correction should be made consistently across all miners and documented as program policy.
Some operations present genuine dual-standard questions. A quarry or mining company that operates a fixed crushing and processing plant that is integral to mining operations falls under MSHA for all workers at that facility. However, if the same company operates a separate ready-mix concrete plant or manufacturing facility that is not integral to the mining operation, those workers fall under OSHA. In these multi-facility situations, employers must apply the correct standard to each workforce segment.
Additionally, some federal contractors performing work at mining sites may face questions about which standard governs. The general rule is that the nature of the work — mining vs. non-mining — determines the governing standard, not the identity of the employer or the location of the work.
Soundtrace provides audiometric surveillance for mining operations under 30 CFR Part 62 — including baseline and annual testing, PLHCP review, reportable hearing loss documentation, and Part 50 filing support.
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