851 Silica Dust Safety in Construction

Glossary

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A

• Action Level (AL). The concentration of respirable crystalline silica in the air, set at 25 micrograms per cubic meter of air (25 ug/m³) as an 8-hour time-weighted average (TWA), which triggers certain OSHA requirements such as exposure monitoring and medical surveillance.
• Administrative Controls. Workplace policies and procedures implemented to reduce worker exposure to hazards, including silica dust, by modifying work schedules, training, and job rotation rather than relying on personal protective equipment or engineering controls.
• Air Monitoring. A method used to measure the concentration of airborne contaminants, such as respirable crystalline silica, to assess worker exposure and ensure compliance with OSHA standards.
• Annual Training. OSHA-required instruction provided at least once a year to educate workers on the health risks of respirable crystalline silica, safe work practices, control measures, and the proper use of personal protective equipment.

B

• Bench Scale Testing. A small-scale method used to evaluate the effectiveness of silica control technologies or substitutes before full implementation in the field or production environment.

C

• Certified Industrial Hygienist (CIH). A professional credentialed by the American Board of Industrial Hygiene, qualified to evaluate workplace health risks, including silica exposure, and recommend appropriate control measures.
• Chest X-Ray. A diagnostic imaging tool used in medical surveillance programs to detect lung damage, such as scarring or fibrosis, caused by long-term exposure to respirable crystalline silica.
• Citation. A formal notice issued by OSHA when an employer is found in violation of workplace safety standards, including failure to comply with the Respirable Crystalline Silica Standard. Citations often come with required abatement actions and potential penalties.
• Compliance Officer. An OSHA representative responsible for inspecting workplaces to ensure that employers are following safety standards, including those related to respirable crystalline silica exposure.
• Competent Person. An individual designated by the employer who is capable of identifying existing and foreseeable silica hazards, and has the authority to take prompt corrective measures to eliminate them, as required by OSHA standards in construction.
• Competent Person Training. Specialized training required for individuals designated as a "competent person" under OSHA's construction silica standard, enabling them to identify silica hazards and implement corrective measures.
• Crystalline Silica. A natural component of soil, sand, granite, and many other minerals. Quartz is the most common form. It becomes hazardous when fine particles are generated and inhaled.

D

• Documentation of Exposure Control Plan. A written record required by OSHA that outlines procedures and controls to protect employees from silica exposure. Employers must review and update this plan regularly and make it accessible to employees and their representatives.
• Dry Cutting. A construction practice involving cutting materials like concrete or stone without using water to suppress dust, which generates high levels of respirable crystalline silica and is generally prohibited or controlled under OSHA regulations.
• Dust Sampling Cyclone. A device used in air monitoring to separate respirable dust particles from larger particles before collection on a filter for analysis of silica concentrations.

E

• Employee Notification. The requirement that employers inform workers of silica exposure monitoring results within five working days of receiving them, as mandated by OSHA's Respirable Crystalline Silica Standard.
• Enclosed Cab. A sealed operator compartment on construction equipment designed to protect workers from airborne dust, including silica, by using HEPA filtration and positive air pressure systems.
• Enforcement Case Database. A public resource maintained by OSHA that provides searchable records of enforcement actions, including those related to silica violations, inspections, citations, and penalties across industries and employers.
• Engineering Controls. Physical changes to the workplace that reduce or eliminate exposure to hazards, such as local exhaust ventilation or water suppression systems used to control silica dust at the source.
• Exposure Assessment. The process required by OSHA to determine employee exposure to respirable crystalline silica through air monitoring or objective data.
• Exposure Control Plan (ECP). A written plan required by OSHA that describes workplace tasks involving silica exposure and outlines the methods used to protect workers, including engineering and administrative controls, PPE, and housekeeping practices.

F

• Fibrosis. The thickening and scarring of lung tissue caused by prolonged exposure to harmful particles such as respirable crystalline silica, often seen in advanced stages of silicosis.

G

• General Duty Clause. A section of the Occupational Safety and Health Act (Section 5(a)(1)) requiring employers to provide a workplace free from recognized hazards, including excessive silica exposure, even in cases where no specific standard exists.
• Gravimetric Sampling. A method used to determine the mass of respirable dust collected on a filter over a given time period, which helps assess a worker's exposure to silica dust.
• Grave Danger Finding. A legal term used by OSHA to justify issuing or updating a standard quickly when a serious health hazard—such as respirable crystalline silica—poses a significant threat to workers' lives or health.

H

• HEPA Filter (High-Efficiency Particulate Air). A filter capable of trapping at least 99.97% of particles that are 0.3 microns in diameter, used in vacuum systems and respirators to capture fine silica dust effectively.

I

• Intentional Violation. A willful breach of OSHA standards where the employer knowingly fails to comply or shows plain indifference to worker safety, such as ignoring known risks related to silica exposure. Willful violations carry the highest penalties.

J

• Jackhammering. A high-risk construction activity that involves breaking up concrete or rock and can release large amounts of respirable silica if not properly controlled with water or dust extraction systems.
• Job Hazard Analysis (JHA). A technique used to identify potential hazards, such as silica exposure, associated with specific job tasks, and to develop controls to reduce worker risk. Required in many safety programs and often reviewed by OSHA inspectors.
• Job Rotation. An administrative control method used to limit individual exposure to hazardous substances, such as respirable crystalline silica, by rotating workers between tasks to reduce total time spent in high-exposure areas.

K

• Key Control Measures. The primary strategies identified in OSHA and NIOSH guidance for reducing silica exposure, including engineering controls (e.g., water suppression, ventilation), administrative controls, and PPE.

L

• Local Exhaust Ventilation (LEV). An engineering control that captures airborne contaminants, such as silica dust, at or near the source and removes them through a duct system to prevent worker exposure.
• Lung Cancer. A serious health condition linked to long-term exposure to respirable crystalline silica, recognized by NIOSH as an occupational hazard and a potential outcome of silica overexposure.

M

• Material Safety Data Sheet (MSDS). A document required by OSHA that provides detailed information about chemical substances, including silica-containing materials, such as health hazards, safe handling practices, and exposure controls. Now replaced by the Safety Data Sheet (SDS) format under the GHS system.

N

• N95 Respirator. A NIOSH-approved filtering facepiece respirator that filters at least 95% of airborne particles, commonly used to protect workers from respirable crystalline silica when engineering controls alone are not sufficient.
• NIOSH (National Institute for Occupational Safety and Health). A federal agency under the CDC that conducts research and makes recommendations to prevent work-related injury and illness, including developing recommended exposure limits (RELs) for respirable crystalline silica.
• NIOSH Certified Respirator. A respiratory protection device approved by NIOSH for use in hazardous environments, including those with respirable crystalline silica, based on strict testing and performance standards.
• NIOSH Hazard Review. A comprehensive document published by NIOSH summarizing scientific evidence, health effects, and control methods for workplace hazards, including respirable crystalline silica, used to inform policy and guidance.

O

• Objective Data. Information such as air monitoring results or industry-wide studies demonstrating expected levels of silica exposure for specific tasks or equipment under specified conditions, which can be used to comply with OSHA silica requirements in lieu of individual exposure monitoring.
• OSHA (Occupational Safety and Health Administration). A federal agency within the U.S. Department of Labor responsible for enforcing workplace safety and health regulations, including the Respirable Crystalline Silica Standard.
• OSHA Final Rule on Silica (2016). The regulation issued by OSHA in 2016 that significantly lowered the permissible exposure limit for respirable crystalline silica and introduced new requirements for engineering controls, training, and medical surveillance. This marked a major regulatory milestone in silica safety.

P

• PEL (Permissible Exposure Limit). The maximum amount of respirable crystalline silica an employee may be exposed to, set by OSHA at 50 micrograms per cubic meter of air (50 ug/m³) averaged over an 8-hour shift.
• Personal Protective Equipment (PPE). Safety gear worn by workers to reduce exposure to hazardous materials, such as respirators, gloves, and protective clothing, when working with or near crystalline silica dust.
• Progressive Massive Fibrosis (PMF). An advanced and severe form of silicosis characterized by large areas of scarring in the lungs, leading to significant breathing difficulties and reduced lung function.

Q

• Qualified Person. An individual with the knowledge, training, and experience to perform specific duties safely and recognize hazards, often used interchangeably with or in addition to "competent person" in some OSHA-related contexts, including silica hazard management.

R

• Recordkeeping Requirements. OSHA regulations that require employers to maintain records of air monitoring data, medical surveillance, and training related to silica exposure for specific periods, often up to 30 years.
• Repeat Violation. A citation issued by OSHA when an employer has been previously cited for the same or a substantially similar condition, including failures related to silica exposure controls, within the past five years.
• Respirable Crystalline Silica. The fraction of crystalline silica particles small enough to penetrate deep into the lungs when inhaled, which can cause serious health issues such as silicosis, lung cancer, and other respiratory diseases.
• Respiratory Protection Program. An OSHA-required plan for employers when respirators are necessary, which includes fit testing, medical evaluations, training, and maintenance procedures to ensure effective protection against airborne silica dust.

S

• Safety Data Sheet (SDS). A standardized document under the Globally Harmonized System (GHS) that replaces the MSDS and provides detailed information on chemical hazards, including those related to silica-containing products. Employers must ensure SDSs are accessible to employees.
• Settlement Agreement. A legal resolution between OSHA and an employer regarding a citation or penalty, sometimes involving reduced fines, abatement actions, or commitments to future compliance with silica standards.
• Silica Rulemaking Docket. The official public record containing all documents, comments, scientific studies, hearing transcripts, and decisions related to the development and adoption of OSHA's Respirable Crystalline Silica Standard.
• Silica Standard. OSHA's regulation that establishes requirements for controlling exposure to respirable crystalline silica in construction and general industry settings, including exposure limits, control methods, and medical surveillance.
• Silicosis. An incurable but preventable lung disease caused by inhaling respirable crystalline silica dust, leading to inflammation and scarring of lung tissue. It is a primary health concern addressed by NIOSH and OSHA silica regulations.
• State Plan States. States that operate their own OSHA-approved occupational safety and health programs. These states must adopt and enforce standards that are at least as effective as federal OSHA's silica standards and may impose additional requirements.
• Substitute Materials. Safer alternatives to silica-containing materials used in construction and manufacturing to reduce exposure risks—for example, using crushed recycled glass instead of sand in abrasive blasting.

T

• Table 1. A part of OSHA's Respirable Crystalline Silica Standard for Construction, listing 18 common construction tasks and specified control measures that, if followed, eliminate the need for exposure monitoring.
• Task-Based Exposure Assessment. An evaluation method that focuses on measuring exposure to silica during specific job tasks rather than full-shift monitoring, often used to inform control strategies under OSHA's silica standard.
• Tool-Mounted Vacuum. A dust control system attached directly to hand tools, such as grinders or saws, which captures silica dust at the point of generation to reduce airborne concentrations. Often equipped with HEPA filters.
• Training Documentation. A written record of completed worker training sessions related to silica hazard communication, control measures, and PPE use. This documentation is required for OSHA compliance and must be kept on file by the employer.

U

• Ultrafine Particles. Extremely small airborne particles, often less than 0.1 microns in diameter, that may be generated during high-energy tasks involving silica-containing materials and pose serious respiratory health risks due to their deep lung penetration.

V

• Vacuum Dust Collection System. A tool-integrated or stand-alone engineering control system designed to capture silica dust at the source using a vacuum and HEPA filtration, commonly used in compliance with OSHA's Table 1.
• Visible Emissions. Dust clouds or particles visible to the naked eye, often indicating uncontrolled silica emissions during cutting, grinding, or demolition. OSHA considers visible dust as a sign of inadequate control measures.

W

• Water Delivery System. An engineering control used to suppress silica dust by applying water directly at the point of cutting, drilling, or grinding, significantly reducing airborne particle generation. Required by OSHA for certain tasks under Table 1.
• Wet Methods. Techniques that use water to control dust generated by cutting, grinding, or drilling silica-containing materials, thereby reducing the inhalation hazard. Recommended by NIOSH and required by OSHA in many construction activities.
• Workplace Hazard Communication Program. An OSHA-mandated system for informing workers about chemical hazards, including respirable crystalline silica, through labels, SDSs, and training as part of the employer's overall safety program.

X

• X-Ray B Reader. A physician certified by NIOSH to classify chest X-rays for pneumoconioses, including silicosis, using standardized criteria in medical surveillance programs.

Y

• Yard Operations. Outdoor industrial activities such as material loading, concrete mixing, or sandblasting that can generate respirable silica. These operations require special attention to dust controls due to environmental exposure factors like wind.

Z

• Zone of Exposure. The area immediately surrounding a task where respirable crystalline silica levels may exceed safe limits. Identifying and managing this zone is critical for worker protection, especially when using localized controls like LEV or water suppression.