Back to Basics is a weekly feature that highlights important but possibly overlooked information that any EHS professional should know. This week, we examine silica hazards and compliance with related OSHA standards.
Silica shows up in materials like sand, stone, concrete, and mortar and is used to make artificial stone, bricks, ceramics, glass, and pottery.
Respirable crystalline silica, or very small particles of silica, is a health hazard that shows up in a wide swath of industries. Workplace exposure to respirable crystalline silica poses a risk for several serious silica-related diseases, including:
- Chronic obstructive pulmonary disease (COPD),
- Kidney disease,
- Lung cancer, and
- Silicosis, an incurable lung disease that can lead to disability and death.
Respiratory health researchers released a study in JAMA Intern Med looking at 52 workers in California who were diagnosed with silicosis caused by occupational exposure to respirable silica dust from engineered stone. Of the 52 subjects in the study, 20 suffered progressive massive fibrosis, 11 needed lung transplants, and 10 died because of their silica dust exposures.
Respirable crystalline silica dust is created when cutting, crushing, drilling, grinding, or sawing block, brick, concrete, mortar, rock, and stone. Workplace tasks that can result in workers’ exposure to respirable crystalline silica dust include:
- Abrasive blasting with sand;
- Crushing or cutting stone;
- Drilling into or sanding concrete walls;
- Grinding mortar;
- Manufacturing brick, ceramic products, concrete blocks, or stone countertops; and
- Sawing brick or concrete.
OSHA standards and directives
The Occupational Safety and Health Administration (OSHA) has two occupational health standards for respirable crystalline silica—one for construction and another for general industry and maritime industries.
The agency revised its standards in 2016, lowering the permissible exposure limit (PEL) for respirable crystalline silica to 50 micrograms per cubic meter (µg/m3) as an 8-hour time-weighted average (TWA). Then in 2020, OSHA issued a revised National Emphasis Program (NEP) of enforcement and outreach for both revised standards.
Industries the NEP targets include dozens of manufacturing industries, as well as dentists’ offices; support activities for oil and gas operations; and electric power generation, transmission, and distribution. Also in 2020, the agency issued inspection procedures for enforcement of the respirable crystalline silica standards.
OSHA’s Region 8 office also has a regional emphasis program (REP) for silica exposures in the cut stone and stone products industry (North American Industry Classification System (NAICS) Code 327991). The action offices for the REP are OSHA’s Billings, Montana; Bismarck, North Dakota; Sioux Falls, South Dakota; and Denver and Englewood, Colorado, area offices. The REP even covers establishments with 10 or fewer employees.
Region 8 compliance safety and health officers (CSHO) have inspection procedures in addition to those for the NEP and the silica standards’ inspection procedures. For example, Region 8 CSHOs must evaluate an employer’s procedures for handling and moving slabs of artificial and natural stone and marble—tasks that pose serious struck-by and crushing safety hazards in addition to the health hazards of respirable crystalline silica dust. CSHOs also must evaluate workers’ potential noise exposures during stone fabrication activities and the need for hearing conservation measures.
Last fall, OSHA launched a compliance assistance and enforcement initiative aimed at silica exposures in the engineered stone fabrication and installation industries that supplements enforcement under the NEP. The new initiative establishes procedures for prioritizing federal inspections to identify and ensure the prompt abatement of hazards in industries where workers face exposure to high levels of silica dust.
For the initiative, OSHA’s Office of Statistical Analysis (OSA) compiled a new industry list that area offices use for targeting employers. Inspections under the engineered stone fabrication and installation industries initiative take priority over those for the silica NEP.
State officials have also taken steps to address respirable crystalline silica hazards. This past December, California issued an emergency temporary standard (ETS) for respirable crystalline silica aimed at protecting workers from silicosis that targets the stone fabrication industry.
The state ETS includes requirements for protecting workers engaged in high-exposure tasks such as cutting, grinding, polishing, and cleanup of artificial stone containing more than 0.1% crystalline silica and natural stone containing more than 10% crystalline silica.
Required work practices under the ETS include:
- Using wet methods,
- Properly handling all waste materials,
- Employing safe cleanup housekeeping methods, and
- Monitoring the air to confirm respirable crystalline silica levels are below the emergency rule’s action level.
The ETS also contains respiratory protection requirements such as:
- Use of a full-face, tight-fitting, powered air-purifying respirator (PAPR) or an equally protective alternative;
- Organic vapor cartridge for artificial stonework, with certain exceptions; and
- Use of a supplied-air respirator under certain conditions.
Employers must train employees on the symptoms of respirable crystalline silica exposure and how to prevent exposures, as well as encourage employees to report symptoms of respirable crystalline silica exposure without fear of retaliation.
Additionally, employers must conduct exposure monitoring at least every 12 months to assess the effectiveness of exposure controls. They also must ensure all “high-exposure trigger tasks” are conducted in a clearly designated area with signage warning of respirable crystalline silica hazards.
Communication requirements under the California ETS include ensuring training and information are appropriate for employees’ language and literacy. Employers must include text on signs posted in regulated areas that describe the risks of permanent lung damage and death in both English and Spanish.
Employers must report employees with confirmed silicosis or lung cancer to California’s Division of Occupational Safety and Health (Cal/OSHA) and the California Department of Public Health (CDPH). Healthcare providers contracted by employers to evaluate their employees also must report confirmed cases of silicosis to Cal/OSHA.
If Cal/OSHA investigators observe dry operations in stone fabrication, they can issue an Order Prohibiting Use (OPU). The state agency also may issue an OPU when violations are found related to prohibited activities, respiratory protection, reporting of silicosis, and carcinogen reporting.
OSHA inspections, citations
OSHA can sometimes cite employers for respirable crystalline silica exposures following inspections for other safety and health hazards. For example, while investigating an amputation injury at a Marinette, Wisconsin, foundry, OSHA inspectors opened a second inspection under the agency’s primary metals industry NEP. The primary metals industry NEP references the respirable crystalline silica NEP and includes procedures for identifying and evaluating silica exposures.
The agency found respirable crystalline silica exposures at the foundry that exceeded the PEL. OSHA also found respirable crystalline silica exposures due to inadequate engineering and administrative controls, dry sweeping, and cleaning with compressed air.
In 2019, OSHA found that workers at a Mount Vernon, Ohio, concrete manufacturing plant were exposed to silica and excessive noise, as well as electrical, mechanical, and respiratory hazards. OSHA determined the employer failed to assess employee exposure to respirable crystalline silica and provide employee training on crystalline silica hazards. The employer also hadn’t provided employees with training and information on the proper care and use of respirators.
Following a workplace fatality investigation in 2022, OSHA determined workers at a Smithfield, Rhode Island, concrete maker were exposed to silica dust. The agency cited the employer with six serious safety and health violations.
Arizona ‘shortcomings’
In 2022, OSHA proposed revoking its approval of the Arizona state workplace safety and health plan. In “state plan” states, the legislatures and state agencies must administer a program “at least as effective” as federal OSHA’s. “Shortcomings in the Arizona plan” included failure to adopt the respirable crystalline silica NEP, as well as failure to adopt the amputations in manufacturing NEP, construction industry beryllium standard, and 2021 healthcare COVID-19 ETS.
Arizona addressed federal OSHA’s concerns, and the federal agency withdrew the proposed revocation last year.
Your silica compliance
Requirements of the general industry and maritime respirable crystalline silica standard include exposure assessment, developing a written exposure control plan, establishing regulated areas, implementing engineering and work practice controls, providing respiratory protection, housekeeping practices, medical surveillance, hazard communication and training, and recordkeeping.
The construction industry standard contains specified exposure control methods for tasks and equipment in Table 1 of the standard. If you choose alternative exposure control methods over methods in Table 1, you must:
- Determine the levels of respirable crystalline silica employees are exposed to.
- Limit employee exposures to a PEL of 50 μg/m3 as an 8-hour TWA.
- Use engineering and work practice controls to limit employee exposures to the PEL, and supplement controls with respiratory protection when necessary.
- Keep records of employee exposure to respirable crystalline silica.
OSHA offers small business compliance guides for both the construction industry and the general industry and maritime silica standards.
Challenges, questions
The 2016 revisions to the silica standards were challenged in federal court by the North America’s Building Trades Union and U.S. Chamber of Commerce. The industry groups lost their challenge in 2017 when the three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit unanimously upheld the OSHA rulemaking, with one exception: The appeals court ordered OSHA to reconsider the standards’ medical removal requirements.
The agency plans to issue a notice of proposed rulemaking this year addressing the court’s concerns.
In 2019, the Trump administration Labor Department issued a request for information seeking feedback on the 2016 revisions. At the time, OSHA asked stakeholders for input on specific control methods for the following equipment and tasks not included in Table 1 of the construction industry standard:
- Mixing of dry materials containing crystalline silica, such as drywall compound, exterior insulation, finishing system base and finish coats, fireproofing, mortar, and plaster.
- Application of shake, such as coloring and/or texturizing material on poured concrete floors.
- Use of chain saws to cut silica-containing materials.
- Use of powered sweepers, or trucks equipped with rotating brushes to clean surfaces.
- Application of dry-mix or wet-mix shotcrete.
- Drywall finishing. OSHA didn’t originally include drywall finishing in Table 1 because drywall compounds containing silica only as a trace contaminant were expected to result in low exposures, but some drywall finishing compounds may have a higher or an unknown silica content.
- Demolition of silica-containing materials using manual tools, such as a chisel, mason hammer, pry bar, or sledgehammer.
- Any other equipment or tasks stakeholders believed should be included in Table 1.
However, other than addressing concerns about the silica standards’ medical removal provisions, OSHA has no silica rulemakings on its regulatory agenda. However, the PEL and the exposure control requirements of the silica standards appear to be set.
You should refer to the construction industry and general industry and maritime standards themselves or OSHA’s small entity compliance guides to ensure you’re in compliance.