Real-time vs. filter-based sampling: what’s better for MSHA silica compliance?

Meeting the new MSHA silica standards requires accurate and actionable data about respirable crystalline silica levels in your mine. 

For decades, filter-based (or gravimetric) sampling has been the preferred method for measuring worker exposures. However, it can be delayed, making it challenging to address overexposures quickly.

In contrast, real-time dust monitoring offers immediate insights that help mines comply with the standard more efficiently.

Here’s a closer look at both approaches and how to use them to comply with silica regulations as efficiently as possible.

Filter-based sampling

Filter-based (gravimetric) sampling involves collecting air samples over a shift using a personal sampling pump, cyclone and cassette with a filter. These samples are collected and then sent to a lab for analysis, where the airborne silica concentration is determined.

This method provides accurate, legally accepted data, but the process has significant drawbacks:

1. Time delays: Results can take days or even weeks to come back, delaying your ability to identify the source of the exposure and implement controls. Imagine explaining to an employee that they were overexposed - two weeks ago. 
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2. Incomplete data: Sampling only provides one average value for an entire shift, making it almost impossible to trace the root cause of overexposures. Repeat sampling is often necessary when overexposures occur.

Filter-based sampling is still helpful for regulatory compliance and can verify that exposure levels meet permissible limits. However, it often falls short when actionable information is required to solve overexposure issues or make confident decisions about engineering controls.

How real-time monitoring works

Real-time monitoring systems continuously measure respirable dust minute by minute. These systems use advanced sensors placed in critical areas or worn by workers, allowing you to track exposure as it happens.

In combination with time-stamped notes and/or bodycam footage, real-time monitoring allows safety and health teams to pinpoint the root cause of overexposures.

Key advantages include:

1. Immediate insights: Instead of waiting on lab results, real-time monitoring streams data directly to the cloud, where you can review it instantly. This allows you to shorten your learning cycles and address overexposures faster.
2. Preventative action: Workers in dusty areas can be notified about high dust concentrations via text or warning lights on their monitor. This can help prevent exposures before they happen and ensure proper respiratory protection for the environment.
3. Long-term costs: While the initial investment may be higher, real-time systems reduce the need for frequent re-sampling. They also allow you to find more efficient engineering controls by pinpointing exposure sources instead of implementing expensive controls based on shift-average samples.

Learn more about real-time monitoring for MSHA silica compliance.

Comparing real-time monitoring and filter-based sampling

When to use each method

Both approaches have their place in your compliance strategy. Filter-based sampling remains essential for fulfilling legal requirements and documenting compliance with regulatory standards. 

However, real-time monitoring is a valuable tool for day-to-day safety management. It helps you identify and resolve overexposures before they become regulatory or health issues and identifies the most cost-effective engineering controls.

For example:

• Scenario 1: Identifying problem areas
  A mine detects unusually high silica levels using real-time monitors in one section of the operation. Addressing the issue immediately—installing localized ventilation and retraining workers on proper practices—reduces exposure levels within weeks.
• Scenario 2: Regulatory validation
  After implementing controls based on real-time monitoring data, filter-based sampling confirms that exposure levels are below the permissible limit, ensuring compliance documentation.

The bottom line

Real-time air quality monitoring doesn’t replace filter-based sampling. Still, making data-based decisions allows you to understand and address exposure sources to get exposures below the MSHA silica limit faster and with verified engineering controls.

By combining gravimetric and real-time sampling methods, mines can stay ahead of MSHA regulations, reduce overexposures, and keep their operations running smoothly.

If your mine still relies on traditional pump and filter sampling alone, it’s time to consider how real-time monitoring could save time, money, and stress in meeting the new MSHA silica rule.

If you’re interested in using real-time monitoring in your mine, book a meeting with our team or get an estimate for your application.