Crystalline silica is an important industrial material found abundantly in the earth’s crust. Quartz, the most common form of silica, is a component of sand, stone, rock, concrete, brick, block, and mortar. Materials containing quartz are found in a wide variety of workplaces.
Silica dust is hazardous when very small (respirable) particles are inhaled. These respirable dust particles can penetrate deep into the lungs and cause disabling and sometimes fatal lung diseases, including silicosis and lung cancer, as well as kidney disease.
Occupational exposure to respirable crystalline silica most often occurs when cutting, sawing, drilling, and crushing of concrete, brick, ceramic tiles, rock, and stone products. Occupational exposure also occurs in operations that process or use large quantities of sand, such as foundries and within the glass, pottery and concrete products industries. The Occupational Safety and Health Administration (OSHA) estimates that more than 2.3 million workers in the United States are potentially exposed to dust containing crystalline silica with nearly 90% of those workers employed in the construction industry.
OSHA issued a final rule on March 24, 2016, to improve protections for workers from exposure to silica on the job. The rule limits the permissible exposure limit for respirable crystalline silica to 50 micrograms per cubic meter of air, which is averaged over an 8-hour shift.
Employers must use controls like water or ventilation to limit exposure and provide respirators when these kinds of engineering controls can’t limit the exposure. They must also have a written plan about possible exposure, provide doctor exams to those exposed and train workers on prevention and possible exposure.
The final rule is written as two standards, one for construction, and one for general industry and maritime. Employers covered by the construction standard have until June 23, 2017 to comply with most requirements. Employers covered by the general industry and maritime standard have until June 23, 2018 to comply with most requirements; additional time is provided to offer medical exams to some workers and for hydraulic fracturing employers to install dust controls to meet the new exposure limit.
- US Department of Labor – Occupational Safety and Health: Silica, Crystalline
- OSHA’s Final Rule to Protect Workers from Exposure to Respirable Crystalline Silica
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This material was produced under grants SH-24385- 13-60- F-34, SH-26288- SH4 and SH-27654- SH5 from the Occupational Safety and Health Administration, US Department of Labor. It does not necessarily reflect the views or policies of the U.S. Department of Labor, nor does mention of trade names, commercial productions, or organizations imply endorsement by the U.S. government.