Silica Standard – At Last!

OSHA published a new standard for crystalline silica today. It’s about time. The standard changes the exposure limit from a complicated formula based on measuring the percentage of quartz in a sample to 0.05 mg/m3, the level NIOSH recommended forty years ago.

We’ve known, for thousands of years, that fine silica dust can damage the lungs. It’s considered a known cause of lung cancer. It’s been linked to kidney disease, and even to an increased risk of tuberculosis. Given the ubiquity of silica, we know we won’t eliminate exposure. But we can control exposure.

Silica shows up in concretes and mortars. It’s naturally present in rocks and sand. It’s a crucial component of glass. Fracking uses silica. The list of industries affected by the standard range from construction to foundries to jewelry production. OSHA estimates over 100,000 workers in general industry and maritime and over two million construction workers are affected by the new standards.

For general industry, the standard is similar to those for other hazardous chemicals, such as lead or hexavalent chromium: first, determine if workers can be overexposed. If they are, use engineering controls and work methods to reduce their exposure. Use housekeeping measures to limit dust. Have a written exposure control plan. Provide medical surveillance. Train workers on the hazards and on ways to reduce their exposure. Use respirators if other control measures aren’t enough.

The construction standard doesn’t require monitoring. Instead, employers can use a control measure that OSHA believes is effective, one specified in the standard.  Those typically incorporate water or dust collection systems to capture or suppress dust.  But employees still need to be trained, medical monitoring is still required, and employers still need to develop a written exposure control plan. In addition, the construction standard requires employers to designate a competent person to go to the job sites, to make sure the exposure control plan is implemented.

For general industry, medical surveillance is required if employees are exposed above the action level of 0.025 mg/m3. For construction, it’s required if employees need to wear respirators for 30 or more days per year. Why the difference? General industry exposures are expected to be consistent. For construction, they’ll vary depending on the task and control measures used.

One of the concerns we’ve had about general industry standards for silica exposure is that those standards are written for a predictable environment. Public Works employees usually don’t do construction work. But they have some exposures that resemble construction – for instance, repairing a concrete sidewalk. The new standard provides for that, allowing employers to comply with the construction standard if the task is one of those listed in the construction standard and if it isn’t “performed regularly in the same environment and conditions.” So as long as our sidewalk repair is done wet, we can be confident that we’re in compliance with the standard.

Construction employers have a year to begin to comply with the standard. General industry has two years, and even longer for some aspects, such as implementing engineering controls.  It’s about time.

Minnesota will need to adopt the new standard. I’d expect MnOSHA to act quickly on this one.







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