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.