Respirable crystalline silica requirements

The respirable crystalline silica standard applies to construction work unless employee exposure will remain below 25 μg/m3 as an 8‑hour TWA under any foreseeable conditions.

• See the scope and application in 1926.1153(a). Employers must evaluate tasks and conditions to determine if exposures can reasonably exceed the action level of 25 μg/m3.

The action level is 25 micrograms per cubic meter (25 μg/m3), calculated as an 8‑hour time‑weighted average (TWA).

• See the definition of action level in 1926.1153(b). Employers use this level to determine when additional monitoring and controls are required.

Employee exposure is the airborne respirable crystalline silica concentration that would occur if the employee were not using a respirator.

• See 1926.1153(b). This means exposure assessments and monitoring must reflect unprotected exposures when deciding controls and medical surveillance needs.

If a task is listed in Table 1, the employer must fully and properly implement the engineering controls, work practices, and respiratory protection specified for that task unless the employer assesses and limits exposures under paragraph (d).

• See the requirement in 1926.1153(c)(1). Implementing Table 1 methods is the default approach for listed tasks unless an exposure assessment using the performance option or scheduled monitoring in 1926.1153(d) shows otherwise.

When a handheld power saw is used outdoors for ≤4 hours per shift, no respirator is required if the employer uses the Table 1 controls (integrated water delivery and proper tool maintenance).

• See the handheld power saw entry in Table 1 of 1926.1153(c)(1). If the task is indoors or the total tasks exceed the time thresholds in 1926.1153(c)(3), higher respiratory protection (APF 10) may be required.

When an employee performs more than one Table 1 task and the combined duration is more than four hours, the respirator required is the one specified for tasks lasting more than four hours; if combined duration is less than four hours, use the respirator specified for ≤4 hours.

• See 1926.1153(c)(3) for the time‑aggregation rule. Track total time on Table 1 tasks during the shift to select the correct Assigned Protection Factor (APF).

An enclosed cab or booth must be kept as free as practicable from settled dust, have working door seals and gaskets, be under positive pressure through continuous fresh air delivery, filter intake air at 95% efficiency for 0.3–10.0 μm, and have heating/cooling.

• See the enclosed cab/booth requirements in 1926.1153(c)(2)(iii) and its subparts (A)–(F). Employers must maintain these features to ensure the cab or booth meaningfully reduces silica exposure.

For indoor tasks, employers must provide exhaust as needed to minimize visible dust accumulation, and when using wet methods they must apply water at flow rates sufficient to minimize visible dust release.

• See 1926.1153(c)(2)(i) and 1926.1153(c)(2)(ii). Employers should verify water flow and exhaust effectiveness as part of routine tool and work practice checks.

Handheld and stand‑mounted drills must use a shroud or cowling with a dust collection system that provides the airflow recommended by the tool manufacturer, has a filter with 99% or greater efficiency and a filter‑cleaning mechanism, and holes must be cleaned with a HEPA‑filtered vacuum.

• See the drill controls in Table 1 under 1926.1153(c)(1)(vii). Follow the tool manufacturer's instructions and maintain the dust system to meet these performance criteria.

Handheld grinders for mortar removal must use a shroud and dust collection system that provides ≥25 cfm per inch of wheel diameter, have a 99%+ efficient filter and a cyclonic pre‑separator or filter‑cleaning mechanism, and require APF 10 for ≤4 hours and APF 25 for >4 hours.

• See the mortar grinder entry in Table 1 of 1926.1153(c)(1)(xi). Employers must keep the dust collector maintained to those airflow and filtration standards.

The PEL for respirable crystalline silica is 50 μg/m3 as an 8‑hour TWA when alternative exposure control methods are used.

• See 1926.1153(d)(1). Employers using methods outside Table 1 must ensure exposures stay at or below this PEL.

The performance option allows employers to assess 8‑hour TWA exposures using any combination of air monitoring data or objective data sufficient to accurately characterize employee exposures.

• See 1926.1153(d)(2)(ii). "Objective data" can include industry monitoring, product composition calculations, or other valid data that reflect workplace conditions equal to or higher than the employer's operations.

Initial monitoring must use one or more personal breathing zone samples that reflect exposures of employees on each shift, for each job classification, and in each work area; employers may sample a representative fraction of employees who perform the same tasks, but must sample those expected to have the highest exposures.

• See 1926.1153(d)(2)(iii)(A). This ensures initial data capture worst‑case exposures to determine need for controls or monitoring frequency.

If initial monitoring shows exposures below the action level, the employer may discontinue monitoring for those employees. If exposures are at/above the action level but ≤ PEL, repeat monitoring within 6 months; if above the PEL, repeat within 3 months. If two consecutive non‑initial measurements seven or more days apart are below the action level, the employer may discontinue monitoring except as paragraph (d)(2)(iv) provides.

• See monitoring frequency rules in 1926.1153(d)(2)(iii)(B)–(E). Maintain records of results and follow reassessment triggers in 1926.1153(d)(2)(iv).

Objective data is information (like industry air monitoring or calculations based on material composition) demonstrating employee exposures for a specific product, material, or process, and it may be used when it reflects workplace conditions closely resembling or having higher exposure potential than the employer's operations.

• See the definition in 1926.1153(b) and its use in the performance option at 1926.1153(d)(2)(ii). Employers must document how the objective data matches their workplace and why it accurately characterizes exposures.

A competent person is someone capable of identifying current and foreseeable respirable crystalline silica hazards and authorized to take prompt corrective actions; they must have the knowledge and ability to fulfill responsibilities in paragraph (g).

• See the competent person definition in 1926.1153(b) and consult 1926.1153(g) for duties the competent person must perform (e.g., worksite inspections, exposure control verification).

A HEPA filter is one that is at least 99.97% efficient in removing mono‑dispersed particles of 0.3 micrometers in diameter.

• See the HEPA filter definition in 1926.1153(b). Use HEPA filtration in vacuums and dust collection systems where the standard requires HEPA‑filtered equipment (for example in cab/booth intake or clean-up operations).

For heavy equipment used to abrade or fracture silica‑containing materials or during demolition, employers must operate the equipment from within an enclosed cab; when employees are outside the cab, apply water and/or dust suppressants to minimize dust. For grading/excavating (not demolishing/abrading), apply water/dust suppressants or, if operator is the only employee, operate from an enclosed cab.

• See the heavy equipment entries in Table 1 under 1926.1153(c)(1)(xvii–xviii). Ensure cabs meet the enclosed cab requirements in 1926.1153(c)(2)(iii).

If not fully implementing Table 1, the employer must use alternative exposure control methods and ensure no employee is exposed above the 50 μg/m3 PEL and must perform an exposure assessment under paragraph (d)(2).

• See the alternative methods and PEL in 1926.1153(d). The employer must then use either the performance option or scheduled monitoring to characterize exposures.

If exposures are at/above the action level but ≤ PEL, repeat monitoring within six months; if exposures are above the PEL, repeat monitoring within three months.

• See the required repeat monitoring intervals in 1926.1153(d)(2)(iii)(C)–(D). Employers must act on results and adjust controls or respiratory protection as needed.

An employer can discontinue monitoring after two consecutive (non‑initial) measurements taken seven or more days apart that are below the action level; until then, monitoring must continue according to the schedule.

• See the discontinuation rule in 1926.1153(d)(2)(iii)(E). Keep records of all monitoring to document compliance.

For handheld power saws cutting fiber‑cement board outdoors, the employer must use a saw with a commercially available dust collection system that provides the tool manufacturer's recommended airflow and a filter with 99%+ efficiency; when these Table 1 controls are used for outdoor cutting of fiber‑cement (blade ≤8 inches), no respirator is required for either ≤4 hours or >4 hours.

• See the specific fiber‑cement saw entry in Table 1 of 1926.1153(c)(1)(iii). Ensure the dust collector is maintained per the tool maker’s airflow specifications.

Cab intake air must be filtered through a filter that is 95% efficient in the 0.3–10.0 μm range (for example, MERV‑16 or better).

• See filtration requirement in 1926.1153(c)(2)(iii)(E) and the HEPA/filter definitions in 1926.1153(b). Maintain filters and seals to preserve cab positive pressure and filtration effectiveness.

When sampling a representative fraction of employees who perform the same tasks on the same shift and in the same work area, the employer must sample the employee(s) expected to have the highest exposure to respirable crystalline silica.

• See representative sampling guidance in 1926.1153(d)(2)(iii)(A). This ensures monitoring captures the upper end of exposure for that group.

Rig‑mounted core saws or drills must be equipped with an integrated water delivery system that supplies water to the cutting surface and be operated and maintained per the manufacturer's instructions; when these controls are used, no respirator is required for either ≤4 hours or >4 hours.

• See the rig‑mounted core saw/drill entry in Table 1 of 1926.1153(c)(1)(vi). Ensure continuous water delivery and tool maintenance to minimize dust.

When walk‑behind milling machines and floor grinders are used indoors or in an enclosed area, employers must use a HEPA‑filtered vacuum to remove loose dust in between passes.

• See the indoor use requirements in Table 1, 1926.1153(c)(1)(xiii). Using HEPA vacuuming helps prevent dust re‑suspension and reduces worker exposures.

Crushing machines must use equipment designed to deliver water spray or mist at crushers and other dust generation points, operate and maintain equipment according to the manufacturer, and provide a ventilated booth or remote control station for the operator.

• See the crushing machines entry in Table 1 of 1926.1153(c)(1)(xvi). Employers must ensure water spray and ventilation are functioning and that operators have protected workstations.

The employer must reassess exposures whenever a change in production, process, control equipment, personnel, or work practices may reasonably be expected to create new or additional exposures at or above the action level, or whenever the employer has any reason to believe such new or additional exposures have occurred. See 1926.1153(d).

• Examples of triggers include new tasks or tools, changes in ventilation or controls, new workers on a task, or a change in materials or work schedules.
• Reassessment should use monitoring or objective data as appropriate to determine whether exposures actually increased.

All samples taken to satisfy the monitoring requirements must be evaluated by a laboratory that analyzes respirable crystalline silica air samples in accordance with the procedures in appendix A to the standard. See 1926.1153(d)(2)(v).

• Use only labs that follow the specified appendix A procedures for sample preparation and analysis to ensure valid results.
• Maintain chain-of-custody and documentation so results can be traced back to the required analysis method.

Employers must individually notify each affected employee in writing of the results within five working days after completing an exposure assessment, or post the results where all affected employees can access them; if exposures exceed the PEL the notice must describe the corrective action being taken. See 1926.1153(d)(2)(vi)(A) and 1926.1153(d)(2)(vi)(B).

• The written notice can be an individual letter or a clearly posted report; choose the method that ensures affected employees actually receive the information.
• If results are above the PEL, include what corrective controls or actions will be used to reduce exposures.

Affected employees or their designated representatives have the right to observe any monitoring of employee exposure to respirable crystalline silica, and if observing requires entry into an area where protective clothing or equipment is required, the employer must provide that protective clothing and equipment at no cost and ensure the observer uses it. See 1926.1153(d)(2)(vii)(A) and 1926.1153(d)(2)(vii)(B).

• Observers should be given instructions about PPE and any site-specific hazards before entry.
• The employer remains responsible for observer safety and must ensure observers follow site PPE rules.

Yes. Employers must use feasible engineering and work practice controls to reduce and maintain employee exposure to respirable crystalline silica to or below the PEL; if those controls alone can’t achieve the PEL they must still be used to reduce exposures as much as feasible and be supplemented with respirators. See 1926.1153(d)(3)(i).

• Controls include local exhaust, wet methods, on-tool vacuum systems, and process changes that reduce dust generation.
• Respirators are a supplement only when controls cannot fully reduce exposures to the PEL.

Respirators are required when Table 1 specifies them for a task or for tasks not listed in Table 1 where exposures exceed the PEL during times needed to implement controls, where controls are not feasible (e.g., certain maintenance), or where all feasible controls are used but still do not reduce exposure to the PEL. See 1926.1153(e)(1)(i) and 1926.1153(e)(1)(ii).

• For listed tasks, follow Table 1 exactly when fully and properly implemented.
• For unlisted or maintenance tasks, provide respirators where controls are infeasible or inadequate.

When respirator use is required by the silica standard, the employer must implement a respiratory protection program in accordance with 29 CFR [1910.134]. See 1926.1153(e)(2) and 1910.134.

• The program must include medical evaluations, fit testing, training, selection of appropriate respirators, maintenance, and recordkeeping as required by 1910.134.
• Follow the specific respirator selection and use provisions in 1910.134(d).

If the employer fully and properly implements the engineering controls, work practices, and respiratory protection described in Table 1 for the listed tasks, the employer is considered to be in compliance with paragraph (e)(1) of the silica standard and with the respirator selection requirements in 1910.134(d)(1)(iii). See the silica standard statement: "For the tasks listed in Table 1... the employer shall be considered to be in compliance..." ([1926.1153], https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.1153).

• This means using the exact controls and respirators described in Table 1 relieves the employer from performing additional exposure-based respirator selection for those tasks, provided they are implemented exactly and fully.
• If an employer deviates from Table 1 methods or cannot fully implement them, the employer must follow the exposure-based obligations in the standard and 1910.134.

(See 1926.1153 for the Table 1 compliance provision.)

Employers must not allow dry sweeping or dry brushing where that activity could contribute to silica exposure unless wet sweeping, HEPA-filtered vacuuming, or other methods that minimize exposure are not feasible; compressed air is also prohibited for cleaning clothing or surfaces that could contribute to exposure unless used with ventilation that captures the dust cloud or no alternative is feasible. See 1926.1153(f)(1) and 1926.1153(f)(2).

• Use wet methods or vacuums with HEPA filtration when cleaning dust.
• If compressed air is necessary, use it with an effective ventilation system that captures the created dust cloud or demonstrate that no alternative is feasible per 1926.1153(f)(2)(i)-(ii).

The written exposure control plan must describe the tasks that involve respirable crystalline silica, the engineering controls/work practices and respiratory protection used for each task, the housekeeping measures used, and the procedures to restrict access to work areas when necessary to minimize exposures. See 1926.1153(g)(1)(i)-(iv).

• Make the plan task-specific (identify who does each task and how exposures are controlled).
• Include practical access restrictions and housekeeping schedules to limit exposure to other employees and other employers on site.

The employer must review and evaluate the effectiveness of the written exposure control plan at least annually and update it as necessary, must make the plan readily available for examination and copying by each covered employee and their representatives, and must designate a competent person to conduct frequent and regular inspections to implement the plan. See 1926.1153(g)(2), 1926.1153(g)(3), and 1926.1153(g)(4).

• Keep records of annual reviews and any updates made.
• Ensure the competent person conducting inspections is trained and authorized to correct problems or require changes.

Employers must provide medical surveillance at no cost and at a reasonable time and place for any employee who will be required to use a respirator for 30 or more days per year, and all medical examinations and procedures must be performed by a PLHCP (physician or other licensed health care professional). See 1926.1153(h)(1)(i) and 1926.1153(h)(1)(ii).

• Track respirator use days to determine who meets the 30-day-per-year trigger.
• Use a PLHCP experienced in occupational respiratory issues to perform required exams.

The employer must make the initial (baseline) medical examination available within 30 days after the employee's initial assignment, unless the employee already had a qualifying examination within the last three years. See 1926.1153(h)(2).

• If an employee has a medical exam meeting the standard’s requirements within three years, that exam can serve as the baseline.
• Schedule baseline exams promptly so they occur within the 30‑day window.

The initial examination must include a medical and work history focusing on silica and respiratory exposures, a physical exam emphasizing the respiratory system, a chest X-ray interpreted by a NIOSH-certified B Reader, pulmonary function testing (FVC and FEV1 with a NIOSH-approved spirometry technician), testing for latent tuberculosis infection, and any other tests the PLHCP deems appropriate. See 1926.1153(h)(2)(i)-(vi).

• Ensure the chest X-ray meets the size and projection requirements and is classified according to the ILO system by a B Reader.
• Use certified technicians and labs for spirometry and radiograph classification.

Periodic medical exams (including the procedures described in paragraph (h)(2), except latent TB testing) must be made available at least every three years or more frequently if the PLHCP recommends it. The employer must provide the PLHCP with a copy of the silica standard and information about the employee’s duties, past/current/anticipated silica exposure levels, any PPE used, and prior occupational medical exam records. See 1926.1153(h)(3) and 1926.1153(h)(4)(i)-(iv).

• Keep exposure records and PPE history ready to share with the PLHCP.
• Follow PLHCP recommendations for more frequent exams when indicated.

The PLHCP must provide the employee a written medical report explaining the exam results within 30 days of each medical examination performed, including statements about any conditions that increase risk, recommended limits on respirator use or silica exposure, and referral recommendations; the employer must obtain a separate written medical opinion for the employer from the PLHCP within 30 days of the medical examination. See 1926.1153(h)(5) and 1926.1153(h)(6)(i).

• The employee’s report must include recommended limitations and a statement about specialist referral if the chest X‑ray is classified 1/0 or higher.
• The employer’s medical opinion should include fitness-for-duty and respirator-use recommendations while respecting employee confidentiality.

The PLHCP's written medical opinion must contain only the date of the exam, a statement that the exam met the requirements of the standard, and any recommended limitations on the employee’s use of respirators. See 1926.1153(h)(6)(i)(A)-(C).

• If the employee gives written authorization, the PLHCP may also include recommended limits on the employee’s exposure to respirable crystalline silica or a recommendation to see a specialist; see 1926.1153(h)(6)(ii).
• Employers must not include other medical details in the PLHCP’s written opinion beyond what the standard permits.

You must give each employee a copy of the PLHCP’s written medical opinion within 30 days of the medical examination. See 1926.1153(h)(6)(iii).

• If the PLHCP included additional information under (h)(6)(ii), that material is provided only if the employee has given written authorization to include it in the opinion.

If the PLHCP recommends a specialist exam, the employer must make a specialist medical examination available within 30 days of receiving the PLHCP’s written opinion. See 1926.1153(h)(7)(i).

Additional employer duties when a specialist exam is required:

• Provide the specialist with all information the employer was required to give the PLHCP under 1926.1153(h)(4), as stated in 1926.1153(h)(7)(ii).

• Ensure the specialist explains the exam results to the employee and provides a written medical report within 30 days that meets the requirements of 1926.1153(h)(5) (except paragraph (h)(5)(iv)), per 1926.1153(h)(7)(iii).

• Obtain a written opinion from the specialist within 30 days that meets the requirements of 1926.1153(h)(6) (with limited exceptions), per 1926.1153(h)(7)(iv).

• Keep in mind timing: both the specialist’s report to the employee and the employer’s receipt of the specialist’s written opinion are required within 30 days of the specialist exam.

Employers must include respirable crystalline silica in their Hazard Communication Program and ensure employees have access to labels and safety data sheets and receive training that meets the HCS and this standard’s training requirements. See 1926.1153(i)(1).

Training must ensure each covered employee can demonstrate knowledge of at least all of the following: the health hazards of respirable crystalline silica; tasks that could cause exposure; the controls (engineering controls, work practices, and respirators) used; the contents of the silica standard; the identity of the employer’s designated competent person per 1926.1153(g)(4); and the purpose and description of the medical surveillance program. See 1926.1153(i)(2)(i)(A)-(F).

• Employers must also make a copy of the silica standard readily available to each covered employee at no cost, per 1926.1153(i)(2)(ii).

Air monitoring records must include the date of each measurement, the task monitored, the sampling and analytical methods used, the number/duration/results of samples, the identity of the laboratory that performed the analysis, the type of PPE (such as respirators) worn by monitored employees, and the names and job classifications of all employees represented by the monitoring (indicating which employees were actually monitored). See 1926.1153(j)(1)(ii)(A)-(G).

• Employers must make and maintain accurate records of all exposure measurements taken per 1926.1153(j)(1)(i).
• Those exposure records must be maintained and made available in accordance with 29 CFR 1910.1020, which governs access to employee exposure and medical records.

If you rely on objective data to demonstrate compliance, you must keep accurate records that include at least the crystalline silica–containing material in question; the source of the objective data; the testing protocol and results; a description of the process, task, or activity on which the objective data were based; and any other relevant data about the process or exposures. See 1926.1153(j)(2)(ii)(A)-(E).

• Objective data must be made and maintained in accordance with 29 CFR 1910.1020 per 1926.1153(j)(2)(iii).

For each employee covered by medical surveillance, the employer must make and maintain an accurate record that includes the employee’s name, copies of the PLHCP’s and specialists’ written medical opinions, and copies of the information provided to those clinicians. See 1926.1153(j)(3)(ii)(A)-(C).

• Employers must ensure these medical records are maintained and made available in accordance with 29 CFR 1910.1020, which sets employee access and confidentiality rules for exposure and medical records.
• Keep records accurate and organized so you can provide access when required by the rule.