Chemicals

Understand the Hazards of Silica

Each year, more than 300 American workers die from silicosis, and thousands of new cases are diagnosed. Silicosis is the name given to incurable lung damage that occurs when workers inhale dusts that contain crystalline silica.

Silica comes in different forms, but crystalline silica is the type that causes scarring in the lungs. Crystalline silica is found in granite, sandstone, quartzite, and various other rocks and sand. Workers who inhale very small crystalline silica particles are at risk for silicosis.

What is Silicosis?

Silicosis is the name given to lung damage that occurs when workers inhale dusts that contain crystalline silica. Workers may not notice symptoms in the disease’s early stages. But after several years of exposure, they will experience shortness of breath, severe cough, chest pain, and fatigue. Exposure to crystalline silica and the development of silicosis also increase their risk of chronic obstructive pulmonary disease (COPD), lung cancer, and tuberculosis.

Silicosis can’t be cured. If a worker’s lungs are so badly damaged that they can no longer function, your only option is a lung transplant. So, it’s important to protect their lungs.


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Industries with Silica Exposures

Workers may be exposed to crystalline silica while they are performing:

  • Construction activities, foundry work, stonecutting, granite countertop fabrication, rock drilling, quarry work, and tunneling. Whenever you perform dust-generating activities on materials that contain crystalline silica—including fabrication, mixing, moving, and cleanup activities—you can be exposed.
  • Oil and gas extraction. National Institute for Occupational Safety and Health (NIOSH) field studies show that workers may be exposed to dust with high levels of respirable crystalline silica during hydraulic fracturing activities.
  • Abrasive blasting (sandblasting). Exposure can occur both when silica-containing materials are used as blasting agents and when materials that contain crystalline silica, such as concrete, are blasted.

OSHA’s Exposure Limit

OSHA’s current permissible exposure limits (PELs) for respirable silica are 100 micrograms of silica per cubic meter of air averaged over an 8-hour work shift in general industry, and 250 micrograms per cubic meter in shipyards and the construction industry. Employers with workers exposed to silica dust above that level must take steps to reduce exposure.


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In August 2013, the agency proposed to reduce the exposure limit to an 8-hour time weighted average (TWA) of 50 micrograms per cubic meter and create a comprehensive standard for silica exposure, including medical surveillance, worker training, and recordkeeping measures. The revised standard and PEL are not yet finalized.

Tomorrow, we’ll look at control measures that can reduce workers’ exposures.

1 thought on “Understand the Hazards of Silica”

  1. Nice article but up here in British Columbia Canada we have the regs that read as follows, Silica, Crystalline – alpha quartz [14808-60-7; 1317-95-9] and Cristobalite, Respirable [14464-46-1] Revised 2006 0.025 mg/m3

    But you forgot one major industry, “Masonry”. This industry up here has had problems with silica since I can remember. I am an ex mason and now a safety adviser on a hug job site. Just the other day i caught a young worker drilling a hole through a concrete pipe and the silica dust was flying directly into his face. His boss failed to instruct him in the proper procedures to do this task. And they wonder why we as safety personal stop work and orientate the workers all the time and then blame us for the slow down in production. But what don’t realize is, industrial disease cost a lot more and not just in money but life itself.

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