Mine Safety and Health Administration

MSHA Silica Final Rule

Lowering Miners’ Exposure to Respirable Crystalline Silica and Improving Respiratory Protection

Scope: Mining Operations in the United States

What is the MSHA Silica Rule and Why Does It Matter?

The MSHA Silica Final Rule is a critical regulation aimed at reducing miners’ exposure to respirable crystalline silica, a hazardous substance linked to serious health conditions such as silicosis, lung cancer, and other respiratory diseases. This rule establishes clear requirements for monitoring, controlling, and limiting silica exposure in mining environments. By enforcing stringent permissible exposure limits (PEL) and requiring effective engineering controls, the rule seeks to protect worker health, improve safety, and ensure compliance with modern occupational standards. It emphasizes the mining industry’s responsibility to create healthier work environments and reduce long-term health risks for miners.

Who Does the MSHA Silica Rule Apply To?

The rule applies to all mining operations in the United States, including surface and underground mines, where workers are at risk of exposure to respirable crystalline silica. Key stakeholders include mine operators, safety managers, and equipment manufacturers responsible for implementing engineering controls, such as improved ventilation systems or wet drilling techniques. Additionally, miners and regulatory bodies are directly impacted, as the rule ensures workers are equipped with proper training, medical surveillance, and protective measures to mitigate silica-related health risks. Compliance is essential for maintaining workplace safety, adhering to regulatory obligations, and fostering a culture of health and safety in mining operations.

MSHA Silica Rule Requirements

1
2
3
4

Exposure Thresholds:
- - Permissible Exposure Limit: Miners’ exposure to respirable crystalline silica must not exceed 50 micrograms per cubic meter of air (µg/m³), averaged over an 8-hour time-weighted average (TWA).
  - Action Level: If exposure levels reach or exceed 25 µg/m³, averaged over an 8-hour TWA, mine operators are required to implement additional protective measures, including exposure monitoring and medical surveillance.

Exposure Monitoring:
- - Regular sampling will assess miners’ exposure to respirable crystalline silica.
  - Use sampling devices that meet the characteristics of respirable-particle-size-selective samplers as specified in ISO 7708:1995.
Reporting and Recordkeeping:
- - Promptly notify miners of their exposure levels following sampling.
  - Maintain accurate records of all exposure measurements and corrective actions taken. Accredited
    laboratories are held to internationally recognized laboratory standards and must participate in
    quarterly proficiency testing for all analyses within the scope of the accreditation.

Implementation:
- - Under the final rule, the mine operator must install, use, and maintain engineering controls, supplemented by administrative controls, when necessary, to keep each miner’s exposure at or below the PEL.
  - Examples include:
    - Wet drilling techniques to suppress dust generation.
    - Enhanced ventilation systems to dilute and remove airborne contaminants.
Respiratory Protection:
- - When engineering controls cannot maintain exposures at or below the PEL, provide miners with appropriate respiratory protection in accordance with ASTM F3387-19 standards.

Training Programs:
- - Develop and implement training programs to educate miners on:
    - The health hazards associated with respirable crystalline silica exposure.
    - The purpose and description of the medical surveillance program.
    - The proper use and limitations of engineering controls and respiratory protection.
Documentation:
- - Maintain records of all training sessions, including dates and attendees.

Exceed MSHA with BreatheSafe

Permissible Exposure Limit

MSHA

BreatheSafe

Permissible Exposure Limit (PEL): Miners’ exposure to respirable crystalline silica must not exceed 50 micrograms per cubic meter of air (µg/m³), averaged over an 8-hour time-weighted average (TWA).

Action Level: If exposure levels reach or exceed 25 µg/m³, averaged over an 8-hour TWA, mine operators are required to implement additional protective measures, including exposure monitoring and medical surveillance.

✅ TWA measurements:
OnGuard controller monitors and displays advanced air quality data in a Time-Weighted Average (TWA), which can be customised for work shifts ranging from 8 to 12 hours.

✅ High Dust & CO₂ Flush:
OnGuard system automatically activates the high dust or CO₂ concentration flush when it detects a high dust load or CO₂ concentration in the cabin, ensuring optimal air quality at all times.

Monitoring and Reporting

MSHA

BreatheSafe

Exposure Monitoring:
- Regular sampling will assess miners’ exposure to respirable crystalline silica.
- Use sampling devices that meet the characteristics of respirable-particle-size-selective samplers as specified in ISO 7708:1995.
Reporting and Recordkeeping:
- Promptly notify miners of their exposure levels following sampling.
- Maintain accurate records of all exposure measurements and corrective actions taken.

✅ Real-Time Air Quality Monitoring:
BreatheSafe’s range of controllers measures, records and stores real-time data for particulate matter (PM) concentration and PM particle counts.

✅ Up to 6 years of Data Logging:
BreatheSafe’s range of controllers provides real-time air quality monitoring and actively optimises air quality conditions for ideal operator performance. Record and store data for up to 6 years, ensuring comprehensive and reliable recordkeeping.

Engineering Control

MSHA

BreatheSafe

Implementation: Employ feasible engineering controls to reduce and maintain miners’ exposure to respirable crystalline silica at or below the PEL.

Respiratory Protection: When engineering controls cannot maintain exposures at or below the PEL, provide miners with appropriate respiratory protection under ASTM F3387-19 standards.

✅ Engineering Control:
Pressurising cabins with clean, filtered air prevents harmful contaminants like silica dust, SO₂, and other hazardous particles from entering the cabin.

✅ Respiratory Protection:
Positive pressure is an invisible shield, preventing dust ingress and ensuring the operator’s breathing zone remains dust-free.

Training and Education

MSHA

BreatheSafe

Training Programs:
- Develop and implement training programs to educate miners on:
- The health hazards associated with respirable crystalline silica exposure.
- The purpose and description of the medical surveillance program.
- The proper use and limitations of engineering controls and respiratory protection.
Documentation: Maintain records of all training sessions, including dates and attendees.

✅ Operator Training:
We conduct operator training to raise awareness of lung health risks and provide practical solutions to prevent exposure to harmful contaminants, ensuring safer workplaces and healthier communities.

✅ Commissioning System:
Our BeSafe commissioning system documents installations to ensure compliance with industry standards, verify system performance, and support warranty claims. This provides a reliable record for troubleshooting and consistent quality assurance across all projects.

MSHA	BreatheSafe
Permissible Exposure Limit
Permissible Exposure Limit (PEL): Miners’ exposure to respirable crystalline silica must not exceed 50 micrograms per cubic meter of air (µg/m³), averaged over an 8-hour time-weighted average (TWA). Action Level: If exposure levels reach or exceed 25 µg/m³, averaged over an 8-hour TWA, mine operators are required to implement additional protective measures, including exposure monitoring and medical surveillance.	✅ TWA measurements: OnGuard controller monitors and displays advanced air quality data in a Time-Weighted Average (TWA), which can be customised for work shifts ranging from 8 to 12 hours. ✅ High Dust & CO₂ Flush: OnGuard system automatically activates the high dust or CO₂ concentration flush when it detects a high dust load or CO₂ concentration in the cabin, ensuring optimal air quality at all times.
Monitoring and Reporting
Exposure Monitoring: Regular sampling will assess miners’ exposure to respirable crystalline silica. Use sampling devices that meet the characteristics of respirable-particle-size-selective samplers as specified in ISO 7708:1995. Reporting and Recordkeeping: Promptly notify miners of their exposure levels following sampling. Maintain accurate records of all exposure measurements and corrective actions taken.	✅ Real-Time Air Quality Monitoring: BreatheSafe’s range of controllers measures, records and stores real-time data for particulate matter (PM) concentration and PM particle counts. ✅ Up to 6 years of Data Logging: BreatheSafe’s range of controllers provides real-time air quality monitoring and actively optimises air quality conditions for ideal operator performance. Record and store data for up to 6 years, ensuring comprehensive and reliable recordkeeping.
Engineering Control
Implementation: Employ feasible engineering controls to reduce and maintain miners’ exposure to respirable crystalline silica at or below the PEL. Respiratory Protection: When engineering controls cannot maintain exposures at or below the PEL, provide miners with appropriate respiratory protection under ASTM F3387-19 standards.	✅ Engineering Control: Pressurising cabins with clean, filtered air prevents harmful contaminants like silica dust, SO₂, and other hazardous particles from entering the cabin. ✅ Respiratory Protection: Positive pressure is an invisible shield, preventing dust ingress and ensuring the operator’s breathing zone remains dust-free.
Training and Education
Training Programs: Develop and implement training programs to educate miners on: The health hazards associated with respirable crystalline silica exposure. The purpose and description of the medical surveillance program. The proper use and limitations of engineering controls and respiratory protection. Documentation: Maintain records of all training sessions, including dates and attendees.	✅ Operator Training: We conduct operator training to raise awareness of lung health risks and provide practical solutions to prevent exposure to harmful contaminants, ensuring safer workplaces and healthier communities. ✅ Commissioning System: Our BeSafe commissioning system documents installations to ensure compliance with industry standards, verify system performance, and support warranty claims. This provides a reliable record for troubleshooting and consistent quality assurance across all projects.