['Toxic and Hazardous Substances - OSHA']
['Crystalline Silica']
01/04/2024
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Crystalline silica is a common mineral found in many naturally occurring materials and used in many industrial products and at construction sites. Materials like sand, concrete, stone and mortar contain crystalline silica. Crystalline silica is also used to make products such as glass, pottery, ceramics, bricks, concrete and artificial stone. Industrial sand used in certain operations, such as foundry work and hydraulic fracturing (fracking), is also a source of silica exposure. Inhaling very small (“respirable”) crystalline silica particles, causes multiple diseases, including silicosis, an incurable lung disease that can lead to disability and death. Respirable crystalline silica also causes lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease.
Scope
OSHA’s silica rule applies to all general industry exposures to respirable crystalline silica, except where the employer has objective data demonstrating that employee exposure to respirable crystalline silica will remain below 25 micrograms per cubic meter of air (25 μg/m3) as an 8-hour time-weighted average (TWA) under any foreseeable conditions. Note: The construction industry has a separate standard for silica exposure.
Regulatory citations
- 29 CFR 1910.1053 — Silica (Respirable crystalline)
Key definitions
- Action level: A concentration of airborne respirable crystalline silica of 25 μg/m3, calculated as an 8-hour TWA.
- Employee exposure: The exposure to airborne respirable crystalline silica that would occur if the employee were not using a respirator.
- High-efficiency particulate air [HEPA] filter: A filter that is at least 99.97 percent efficient in removing mono-dispersed particles of 0.3 micrometers in diameter.
- Objective data: Information, such as air monitoring data from industry-wide surveys or calculations based on the composition of a substance, demonstrating employee exposure to respirable crystalline silica associated with a particular product or material or a specific process, task, or activity. The data must reflect workplace conditions closely resembling or with a higher exposure potential than the processes, types of material, control methods, work practices, and environmental conditions in the employer’s current operations.
- Regulated area: An area, demarcated by the employer, where an employee’s exposure to airborne concentrations of respirable crystalline silica exceeds, or can reasonably be expected to exceed, the PEL.
- Respirable crystalline silica: Quartz, cristobalite, and/or tridymite contained in airborne particles that are determined to be respirable by a sampling device designed to meet the characteristics for respirable-particle-size-selective samplers specified in the International Organization for Standardization (ISO) 7708:1995: Air Quality—Particle Size Fraction Definitions for Health-Related Sampling.
Summary of requirements
Employers should:
- Survey your operations for potential exposure to silica. Employers can consult their suppliers or examine material safety data sheets or safety data sheets (MSDSs/SDSs) to identify silica-containing materials that are or could be present in the workplace.
- Measure the amount of silica that workers are exposed to if it may be at or above an action level of 25 μg/m3 (micrograms of silica per cubic meter of air), averaged over an 8-hour day.
- Protect workers from respirable crystalline silica exposures above the permissible exposure limit of 50 μg/m3, averaged over an 8-hour day.
- Limit workers’ access to areas where they could be exposed above the PEL. To minimize any unnecessary employee exposures, the standard for general industry and maritime requires employers to establish a regulated area wherever an employee’s exposure to airborne concentrations of respirable crystalline silica is, or can reasonably be expected to be, in excess of the PEL. The standard requires that employers demarcate the boundaries of the regulated area (as separate from the rest of the workplace), post signs at the entrances to the regulated area, limit access to the regulated area, and provide an appropriate respirator to each employee or employee representative entering the regulated area.
- Use dust controls to protect workers from silica exposures above the PEL. In most cases, dust controls such as wet methods and ventilation can be used to limit workers’ exposure to silica, OSHA says. Note: The construction industry standard for silica includes a table (Table 1) setting out controls for a specified list of tasks, and specifying which of those tasks require respiratory protection to complement the controls in order to maintain exposures at or below the PEL.
- Provide respirators to workers when dust controls cannot limit exposures to the PEL. Respiratory protection must be used in accordance with OSHA’s 1910.134 respiratory protection standard, which includes annual fit testing, medical evaluation, training, selection, maintenance, as well as a written program. Note: Dust masks are considered to be filtering facepiece respirators.
- Restrict housekeeping practices that expose workers to silica where feasible alternatives are available.
- Establish and implement a written exposure control plan that identifies tasks that involve exposure and methods used to protect workers.
- Offer medical exams — including chest X-rays and lung function tests — every three years for workers exposed at or above the action level for 30 or more days per year.
- Train workers on work operations that result in silica exposure and ways to limit exposure. This must follow the 1910.1200 HazCom standard, as well as information on specific exposures, controls, and practices.
- Keep records of workers’ silica exposure and medical exams.
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['Toxic and Hazardous Substances - OSHA']
['Crystalline Silica']
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