By Sy-Klone
Recently, the Mine Safety and Health Administration (MSHA) announced a temporary enforcement pause on their respirable crystalline silica (RCS) rule (89 Fed. Reg. 28,218), designed to protect mine operators from occupational diseases. Mining companies will now have until August 18, 2025, to comply. This brief enforcement pause is a valuable opportunity for companies to reach greater clarity on regulatory requirements and voluntary standards concerning air quality at their mine sites.
For North American mine sites, the MSHA Silica Rule, as it’s commonly known, defines compliance requirements. In doing so, it draws on an important quality standard called ISO 23875, which is recognized as the international benchmark for modern air quality. Using the ISO 23875 standard as a reference for compliance within the Silica Rule enables MSHA to implement a uniform and standardized approach to compliance and enforcement, potentially leading to reduced operator exposures. For mine operators, referencing ISO 23875 as a guide for implementing or maintaining cab air quality systems simplifies the path to demonstrating compliance with the MSHA rule.
Here’s a breakdown of MSHA requirements and a snapshot of ISO 23875 guidelines for designing, testing and maintaining cab air quality management systems.
What MSHA requires
The Silica Rule lowers the permissible exposure limit for RCS to 50 micrograms per cubic meter of air — half the current limit — over an 8-hour time-weighted average. And compliance involves four key steps:
- Perform regular air sampling. Gather the right tools and sample your air for RCS.
- Send samples to lab. Air samples must be evaluated by an ISO 17025-certified lab.
- Review results. Confirm RCS limit results internally and share them with workers.
- Maintain records. Keep clear, complete records to track RCS exposure over time.
If sampling shows that RCS levels are greater than the permissible exposure level, companies must inform MSHA and take immediate action to reduce RCS levels. Failure to comply will introduce serious fines.
What about ISO 23875?
ISO 23875, a voluntary international standard, addresses air quality inside mining equipment operator enclosures, covering RCS as well as other fine particulate matter. It defines five core engineering performance standards:
- CO₂ control.Cab environments must maintain CO₂ below 400 parts per million above ambient air.
- Recirculation efficiency. Recirculated air must be continuously cleaned with high-efficiency filters that can remove fine particulate matter.
- Filter efficiency. Filters must remove at least 94% of particles at 0.3 microns.
- Cab pressurization. The cab must hold a minimum of 20 pascals of pressure at all times.
- Real-time monitoring and alerts. The operator must be alerted when CO₂ and air pressure thresholds are breached.
Created by international mining experts to represent the highest achievable standard of operator air quality, ISO 23875 is widely respected as a gold standard. In practice, aligning with ISO 23875 all but guarantees that sites will pass MSHA audits.
Air quality as a pillar of company culture
Effectively instilling operator safety as a shared priority requires companies to embrace air quality as a pillar of company culture.
Success comes down to a cultural shift across the organization. Supervisors must lead by example, ensuring checks are routine and not just reactive. Operators need solid education to understand why the solutions used to uphold the rule or standard exist so they can respond to alerts and report failures. Meanwhile, maintenance teams should be empowered to diligently track filter performance and document service logs.
Without a shared responsibility for air quality, any standard or rule risks becoming an afterthought.
Building a culture of safety means reminding teams they’re not ticking boxes, but rather protecting lungs, lives and livelihoods.
Your new recruiting advantage? Acting now.
If you’re waiting for the perfect moment to act — don’t. The sooner you begin investing in air quality, the faster your site will gain insight and grow capacity to deliver safety to your operators.
And there’s another upside: a culture of safety is a real magnet for talent. In a competitive labor market with sometimes hazardous working conditions, a truly safe site becomes a serious recruiting advantage.
While MSHA’s Silica Rule and the ISO 23875 standard are well-defined, strong cultures of safety are still rare.
Ready to get ahead of air quality safety now? Get in touch with Sy-Klone and learn how your mine site can exceed air quality and safety standards.
Contact Sy-Klone Today
Phone: (904) 448-6563
Website: https://www.sy-klone.com/
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