§ 1926.1153 Respirable crystalline silica.
(a) Scope and application. This section applies to all occupational exposures to respirable crystalline silica in construction work, except where employee exposure will remain below 25 micrograms per cubic meter of air (25 µg/m ) as an 8-hour time-weighted average (TWA) under any foreseeable conditions.
(b) Definitions. For the purposes of this section the following definitions apply:
Action level means a concentration of airborne respirable crystalline silica of 25 µg/m , calculated as an 8-hour TWA.
Assistant Secretary means the Assistant Secretary of Labor for Occupational Safety and Health, U.S. Department of Labor, or designee.
Director means the Director of the National Institute for Occupational Safety and Health (NIOSH), U.S. Department of Health and Human Services, or designee.
Competent person means an individual who is capable of identifying existing and foreseeable respirable crystalline silica hazards in the workplace and who has authorization to take prompt corrective measures to eliminate or minimize them. The competent person must have the knowledge and ability necessary to fulfill the responsibilities set forth in paragraph (g) of this section.
Employee exposure means the exposure to airborne respirable crystalline silica that would occur if the employee were not using a respirator.
High-efficiency particulate air [HEPA] filter means a filter that is at least 99.97 percent efficient in removing mono-dispersed particles of 0.3 micrometers in diameter.
Objective data means 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.
Physician or other licensed health care professional [PLHCP] means an individual whose legally permitted scope of practice (i.e., license, registration, or certification) allows him or her to independently provide or be delegated the responsibility to provide some or all of the particular health care services required by paragraph (h) of this section.
Respirable crystalline silica means 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.
Specialist means an American Board Certified Specialist in Pulmonary Disease or an American Board Certified Specialist in Occupational Medicine.
This section means this respirable crystalline silica standard, 29 CFR 1926.1153.
(c) Specified exposure control methods. (1) For each employee engaged in a task identified on Table 1, the employer shall fully and properly implement the engineering controls, work practices, and respiratory protection specified for the task on Table 1, unless the employer assesses and limits the exposure of the employee to respirable crystalline silica in accordance with paragraph (d) of this section.
Table 1—Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica
| Equipment/task | Engineering and work practice control methods | Required respiratory protection and minimum assigned protection factor (APF) | |
|---|---|---|---|
| ≤4 hours/shift | >4 hours/shift | ||
| (i) Stationary masonry saws | Use saw equipped with integrated water delivery system that continuously feeds water to the blade | None | None. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| (ii) Handheld power saws (any blade diameter) | Use saw equipped with integrated water delivery system that continuously feeds water to the blade | ||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions: | |||
| —When used outdoors | None | APF 10. | |
| —When used indoors or in an enclosed area | APF 10 | APF 10. | |
| (iii) Handheld power saws for cutting fiber-cement board (with blade diameter of 8 inches or less) | For tasks performed outdoors only: Use saw equipped with commercially available dust collection system Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | None | None. |
| Dust collector must provide the air flow recommended by the tool manufacturer, or greater, and have a filter with 99% or greater efficiency | |||
| (iv) Walk-behind saws | Use saw equipped with integrated water delivery system that continuously feeds water to the blade | ||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions: | |||
| —When used outdoors | None | None. | |
| —When used indoors or in an enclosed area | APF 10 | APF 10. | |
| (v) Drivable saws | For tasks performed outdoors only: | ||
| Use saw equipped with integrated water delivery system that continuously feeds water to the blade | None | None. | |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| (vi) Rig-mounted core saws or drills | Use tool equipped with integrated water delivery system that supplies water to cutting surface | None | None. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| (vii) Handheld and stand-mounted drills (including impact and rotary hammer drills) | Use drill equipped with commercially available shroud or cowling with dust collection system | None | None. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| Dust collector must provide the air flow recommended by the tool manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism | |||
| Use a HEPA-filtered vacuum when cleaning holes | |||
| (viii) Dowel drilling rigs for concrete | For tasks performed outdoors only: | ||
| Use shroud around drill bit with a dust collection system. Dust collector must have a filter with 99% or greater efficiency and a filter-cleaning mechanism | APF 10 | APF 10. | |
| Use a HEPA-filtered vacuum when cleaning holes | |||
| (ix) Vehicle-mounted drilling rigs for rock and concrete | Use dust collection system with close capture hood or shroud around drill bit with a low-flow water spray to wet the dust at the discharge point from the dust collector | None | None. |
| OR | |||
| Operate from within an enclosed cab and use water for dust suppression on drill bit | None | None. | |
| (x) Jackhammers and handheld powered chipping tools | Use tool with water delivery system that supplies a continuous stream or spray of water at the point of impact: | ||
| —When used outdoors | None | APF 10. | |
| —When used indoors or in an enclosed area | APF 10 | APF 10. | |
| OR | |||
| Use tool equipped with commercially available shroud and dust collection system | |||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| Dust collector must provide the air flow recommended by the tool manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism: | |||
| —When used outdoors | None | APF 10. | |
| —When used indoors or in an enclosed area | APF 10 | APF 10. | |
| (xi) Handheld grinders for mortar removal (i.e., tuckpointing) | Use grinder equipped with commercially available shroud and dust collection system | APF 10 | APF 25. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism | |||
| (xii) Handheld grinders for uses other than mortar removal | For tasks performed outdoors only: Use grinder equipped with integrated water delivery system that continuously feeds water to the grinding surface | None | None. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| OR | |||
| Use grinder equipped with commercially available shroud and dust collection system | |||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism: | |||
| —When used outdoors | None | None. | |
| —When used indoors or in an enclosed area | None | APF 10. | |
| (xiii) Walk-behind milling machines and floor grinders | Use machine equipped with integrated water delivery system that continuously feeds water to the cutting surface | None | None. |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| OR | |||
| Use machine equipped with dust collection system recommended by the manufacturer | None | None. | |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions | |||
| Dust collector must provide the air flow recommended by the manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism | |||
| When used indoors or in an enclosed area, use a HEPA-filtered vacuum to remove loose dust in between passes | |||
| (xiv) Small drivable milling machines (less than half-lane) | Use a machine equipped with supplemental water sprays designed to suppress dust. Water must be combined with a surfactant | None | None. |
| Operate and maintain machine to minimize dust emissions | |||
| (xv) Large drivable milling machines (half-lane and larger) | For cuts of any depth on asphalt only: Use machine equipped with exhaust ventilation on drum enclosure and supplemental water sprays designed to suppress dust | None | None. |
| Operate and maintain machine to minimize dust emissions | |||
| For cuts of four inches in depth or less on any substrate: | |||
| Use machine equipped with exhaust ventilation on drum enclosure and supplemental water sprays designed to suppress dust | None | None. | |
| Operate and maintain machine to minimize dust emissions | |||
| OR | |||
| Use a machine equipped with supplemental water spray designed to suppress dust. Water must be combined with a surfactant | None | None. | |
| Operate and maintain machine to minimize dust emissions | |||
| (xvi) Crushing machines | Use equipment designed to deliver water spray or mist for dust suppression at crusher and other points where dust is generated (e.g., hoppers, conveyers, sieves/sizing or vibrating components, and discharge points) | None | None. |
| Operate and maintain machine in accordance with manufacturer's instructions to minimize dust emissions | |||
| Use a ventilated booth that provides fresh, climate-controlled air to the operator, or a remote control station | |||
| (xvii) Heavy equipment and utility vehicles used to abrade or fracture silica-containing materials (e.g., hoe-ramming, rock ripping) or used during demolition activities involving silica-containing materials | Operate equipment from within an enclosed cab When employees outside of the cab are engaged in the task, apply water and/or dust suppressants as necessary to minimize dust emissions | None None | None. None. |
| (xviii) Heavy equipment and utility vehicles for tasks such as grading and excavating but not including: Demolishing, abrading, or fracturing silica-containing materials | Apply water and/or dust suppressants as necessary to minimize dust emissions OR | None | None. |
| When the equipment operator is the only employee engaged in the task, operate equipment from within an enclosed cab | None | None. | |
(2) When implementing the control measures specified in Table 1, each employer shall:
(i) For tasks performed indoors or in enclosed areas, provide a means of exhaust as needed to minimize the accumulation of visible airborne dust;
(ii) For tasks performed using wet methods, apply water at flow rates sufficient to minimize release of visible dust;
(iii) For measures implemented that include an enclosed cab or booth, ensure that the enclosed cab or booth:
(A) Is maintained as free as practicable from settled dust;
(B) Has door seals and closing mechanisms that work properly;
(C) Has gaskets and seals that are in good condition and working properly;
(D) Is under positive pressure maintained through continuous delivery of fresh air;
(E) Has intake air that is filtered through a filter that is 95% efficient in the 0.3-10.0 µm range (e.g., MERV-16 or better); and
(F) Has heating and cooling capabilities.
(3) Where an employee performs more than one task on Table 1 during the course of a shift, and the total duration of all tasks combined is more than four hours, the required respiratory protection for each task is the respiratory protection specified for more than four hours per shift. If the total duration of all tasks on Table 1 combined is less than four hours, the required respiratory protection for each task is the respiratory protection specified for less than four hours per shift.
(d) Alternative exposure control methods. For tasks not listed in Table 1, or where the employer does not fully and properly implement the engineering controls, work practices, and respiratory protection described in Table 1:
(1) Permissible exposure limit (PEL). The employer shall ensure that no employee is exposed to an airborne concentration of respirable crystalline silica in excess of 50 µg/m , calculated as an 8-hour TWA.
(2) Exposure assessment—(i) General. The employer shall assess the exposure of each employee who is or may reasonably be expected to be exposed to respirable crystalline silica at or above the action level in accordance with either the performance option in paragraph (d)(2)(ii) or the scheduled monitoring option in paragraph (d)(2)(iii) of this section.
(ii) Performance option. The employer shall assess the 8-hour TWA exposure for each employee on the basis of any combination of air monitoring data or objective data sufficient to accurately characterize employee exposures to respirable crystalline silica.
(iii) Scheduled monitoring option. (A) The employer shall perform initial monitoring to assess the 8-hour TWA exposure for each employee on the basis of one or more personal breathing zone air samples that reflect the exposures of employees on each shift, for each job classification, in each work area. Where several employees perform the same tasks on the same shift and in the same work area, the employer may sample a representative fraction of these employees in order to meet this requirement. In representative sampling, the employer shall sample the employee(s) who are expected to have the highest exposure to respirable crystalline silica.
(B) If initial monitoring indicates that employee exposures are below the action level, the employer may discontinue monitoring for those employees whose exposures are represented by such monitoring.
(C) Where the most recent exposure monitoring indicates that employee exposures are at or above the action level but at or below the PEL, the employer shall repeat such monitoring within six months of the most recent monitoring.
(D) Where the most recent exposure monitoring indicates that employee exposures are above the PEL, the employer shall repeat such monitoring within three months of the most recent monitoring.
(E) Where the most recent (non-initial) exposure monitoring indicates that employee exposures are below the action level, the employer shall repeat such monitoring within six months of the most recent monitoring until two consecutive measurements, taken seven or more days apart, are below the action level, at which time the employer may discontinue monitoring for those employees whose exposures are represented by such monitoring, except as otherwise provided in paragraph (d)(2)(iv) of this section.
(iv) Reassessment of exposures. The employer shall reassess exposures whenever a change in the production, process, control equipment, personnel, or work practices may reasonably be expected to result in new or additional exposures at or above the action level, or when the employer has any reason to believe that new or additional exposures at or above the action level have occurred.
(v) Methods of sample analysis. The employer shall ensure that all samples taken to satisfy the monitoring requirements of paragraph (d)(2) of this section are evaluated by a laboratory that analyzes air samples for respirable crystalline silica in accordance with the procedures in appendix A to this section.
(vi) Employee notification of assessment results. (A) Within five working days after completing an exposure assessment in accordance with paragraph (d)(2) of this section, the employer shall individually notify each affected employee in writing of the results of that assessment or post the results in an appropriate location accessible to all affected employees.