Crystalline silica is a common mineral found in the earth's crust. Materials like sand, stone, concrete, and mortar contain crystalline silica. It is also used to make products such as glass, pottery, ceramics, bricks, and artificial stone. It is most commonly found in nature as quartz and in various living organisms In many parts of the world, silica is the major constituent of sand. Notable examples include alpha quartz and high-temperature minerals like cristobalite and tridymite. Crystalline silica is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries. Inhaling finely divided crystalline silica is toxic and can lead to severe inflammation of the lung tissue, silicosis, bronchitis, lung cancer, and systemic autoimmune diseases, such as lupus and rheumatoid arthritis.

 

Respirable crystalline silica – very small particles at least 100 times smaller than ordinary sand you might find on beaches and playgrounds – is created when cutting, sawing, grinding, drilling, and crushing stone, rock, concrete, brick, block, and mortar. Activities such as abrasive blasting with sand; sawing brick or concrete; sanding or drilling into concrete walls; grinding mortar; manufacturing brick, concrete blocks, stone counter tops, or ceramic products; and cutting or crushing stone result in worker exposures to respirable crystalline silica dust. Industrial sand used in certain operations, such as foundry work and hydraulic fracturing (fracking), is also a source of respirable crystalline silica exposure. About 2.3 million people in the U.S. are exposed to silica at work.

 

Workers who inhale these very small crystalline silica particles are at increased risk of developing serious silica-related diseases, including:

 

• Silicosis, an incurable lung disease that can lead to disability and death;

• Lung cancer;

• Chronic obstructive pulmonary disease (COPD); and

• Kidney disease.

 

On March 25, 2016, the Occupational Safety and Health Administration (OSHA) published two separate final rule regulating occupational exposure to respirable crystalline silica (silica) in the construction industry and for the general industry and maritime industries (29 C.F.R. § 1910.1053). While there are differences between the two standards, they both require compliance with the following exposure limits in the OSHA standard

​

• ​AL - action level (25 μg/m3 as an 8-hour time-weighted average)

• PEL - permissible exposure limit (50 μg/m3 as an 8-hour time-weighted average)

• TWA - time-weighted average

 

The OSHA standard permits construction employers to select from two methods of compliance to control exposures to respirable crystalline silica: "specified exposure control methods" or "alternative exposure control methods." Under "specified exposure control methods," employers can comply by fully and properly implementing the engineering controls, work practices, and respiratory protection set forth for the relevant task on "Table 1." 29 C.F.R. § 1926.1153(c). Employers following Table 1 do not have to assess employee exposures or separately ensure compliance with the PEL. Table 1 includes common construction tasks.

​

Scope (29 C.F.R. § 1926.1153(a)) OSHA's silica standard for construction applies to all occupational exposures to respirable crystalline silica in construction work, except where employee exposures will remain below the AL of 25 μg/m3, calculated as an 8-hour TWA, under any foreseeable conditions. 29 C.F.R. § 1926.1153(a). The exception applies only where exposures below 25 μg/m3 as an 8-hour TWA are expected or achieved without using engineering or other controls. The exception is intended to ensure that the standard does not apply to employees whose work results in only minimal silica exposures. See 81 Fed. Reg. at 16706.

​

The Windsor Consulting Group, Inc. can conduct air and surface testing for the presence or absence of respirable crystalline silica materials. We also collect bulk samples during our preliminary investigation to determine, which if any building material contains various quantities and types of crystalline silica. Our Certified Industrial Hygienists (CIHs) can conduct an exposure risk assessment of the at-ris workforce and determine which engineering and/or administrative controls are most cost-efficient.