Generally, yes. The intent of the standard is to exempt conditions where employees will be exposed to minimal levels of silica under any foreseeable conditions. Although engineering controls are usually a reliable means of limiting employee exposures, equipment does occasionally fail (e.g., due to a gradual deterioration in effectiveness attributable to poor maintenance or failure to follow standard operating procedures). Because OSHA considers the failure of most controls to be a foreseeable condition, the exception usually applies only where exposures below 25 μg/m³ as an 8-hour TWA are expected or achieved without the use of controls. Operations where engineering controls have been implemented specifically for the purpose of reducing exposures to silica will typically be covered by the standard, because the failure to properly implement, operate, and maintain those controls would generally be expected to result in exposures at or above 25 μg/m³ as an 8-hour TWA. For example, if an employer controls employee silica exposures using local exhaust ventilation or a conveyor containment system, OSHA considers the failure of those controls to be a foreseeable condition, and the employer will not be exempt from the standard on the basis of data showing that exposures are below 25 μg/m³ as an 8-hour TWA when the ventilation or containment system is used.

However, failure of some types of controls (e.g., substitution of non-silica-containing materials for materials that contain silica, fixed walls that are a permanent part of a building's structure) is not possible or so improbable that it is not a foreseeable condition, and therefore employers need not account for the potential failure of such controls when determining whether employee exposure to silica will remain below 25 μg/m³ measured as an 8-hour TWA under any foreseeable conditions. Furthermore, in determining whether the standard applies, employers do not need to disable, remove, or otherwise account for the potential failure of measures that may contribute, in a limited fashion, to reducing silica exposures, but that are not adopted for that specific purpose, i.e., general building ventilation or heating, ventilation, and air conditioning (HVAC) systems.

Thus, with very limited exceptions, any objective data used to demonstrate that employee exposure to silica will remain below 25 μg/m³ measured as an 8-hour TWA under any foreseeable conditions must represent employee exposures that exist in the absence of controls.

The standard does not include a specific exemption for tasks with only short-term exposures (e.g., tasks with exposure for 15 minutes a day or less). However, the standard does not apply where the employer has objective data demonstrating that employee exposure to respirable crystalline silica will remain below 25 μg/m³ as an 8-hour TWA under any foreseeable conditions. Short-term silica exposures must be very high in order for those exposures to reach or exceed 25 μg/m³ as an 8-hour TWA; for example, if an employee is exposed for only 15 minutes, his or her exposure would have to be higher than 800 μg/m³ for that 15-minute period before the 8-hour TWA exposure would be at or above 25 μg/m³. See 81 Fed. Reg. at 16706. Some examples of tasks that could generate very high short-term exposures include abrasive blasting and grinding engineered stone countertops, which are typically associated with high levels of visible dust

Workers may perform maintenance tasks involving occasional, brief exposures to silica that are incidental to their primary work. Provided that these employees perform these tasks in isolation from activities that generate significant exposures to silica, and perform them for no more than 15 minutes throughout the work day, their exposures will usually fall below the AL of 25 μg/m³ as an 8-hour TWA under all foreseeable conditions. When employers obtain or develop objective data showing that exposures will remain below the AL under any foreseeable conditions, these employees will not be covered by the standard.

Yes. The standard's exception for exposures below the AL applies only if the employer has documentation (i.e., objective data) demonstrating that employees' silica exposures will remain below the AL of 25 μg/m³ as an 8-hour TWA under any foreseeable conditions. (Note that documentation is required only when employees have some level of occupational exposure to silica. The standard does not apply to employees who have no occupational exposure.) Also, nothing in the silica standard alters employers' duty to maintain employee exposure records under 29 C.F.R. § 1910.1020.

No. None of the standard's requirements apply where the employer has objective data demonstrating that all employees' exposures to silica will remain below the AL of 25 μg/m³ as an 8-hour TWA under any foreseeable conditions.

Yes. The standard does not require employers to independently test the effectiveness of filters to determine if they meet the definition in paragraph (b). Employers can rely on a manufacturer's representation that a filter is at least 99.97 percent efficient in removing mono-dispersed particles of 0.3 micrometers in diameter or that it is compliant with the OSHA definition of a "HEPA filter." However, employers must properly select, use, maintain, and replace HEPA filters in order to ensure that they continue to function according to the manufacturer's specifications.

Yes, as long as the employer ensures that each employee's exposures are adequately assessed. The employer may determine the optimal approach for assessing each employee's silica exposures. This means that, for each individual employee, the employer may choose to use either the performance option under paragraph (d)(2) or the scheduled monitoring option under paragraph (d)(3).

Yes. The employer has the option of switching to the performance option, and can use air monitoring data generated during scheduled monitoring to fulfill assessment requirements under the performance option, provided that the air monitoring data relied on is sufficient to accurately characterize employee exposures. Whether an employer's air monitoring data accurately reflect current exposures depends on several factors, including the degree to which exposures vary by day, shift, or process; work practices used; or the condition of equipment. Furthermore, when following either exposure assessment option under the silica standard, the employer must reassess exposures following any changes in the production, process, control equipment, personnel, or work practices that may reasonably be expected to result in new or additional exposures to silica at or above the AL, or when the employer has any reason to believe that new or additional exposures at or above the AL have occurred. See 29 C.F.R. § 1910.1053(d)(4).

Under the performance option, the employer must assess each employee's 8-hour TWA exposure using any combination of air monitoring data or objective data, provided that the data is sufficient to accurately characterize employee exposures to silica. See 29 C.F.R. § 1910.1053(d)(2). Any data used to assess exposures under the performance option must accurately reflect existing workplace conditions. See 81 Fed. Reg. at 16764.

The term "air monitoring data" refers to any monitoring conducted by the employer to comply with the requirements of this standard, including the prescribed accuracy and confidence requirements (see 29 C.F.R. § 1910.1053(d)(5), Appendix A).

The term "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 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. See 29 C.F.R. § 1910.1053(b). Types of data and exposure assessment strategies that may qualify as objective data include:

• Data from industry-wide surveys;
• Data provided by equipment manufacturers;
• Data provided by trade or professional associations;
• Exposure mapping (determining exposures associated with particular locations based on information obtained from sources that may include personal samples, area samples, and direct- reading instruments);
• Calculations based on the composition of a substance;
• Calculations based on the chemical and physical properties of a substance (in those instances where a substance's physical and chemical properties demonstrate employee exposure to silica associated with a particular product or material or a specific process, task, or activity); and
• The employer's historical air monitoring data, including data obtained prior to the effective date of the standard.

The preamble to the standard provides more ideas about data and exposure assessment strategies that could qualify as or generate objective data. See 81 Fed. Reg. at 16763. OSHA notes that the same types of objective data that can be used to assess employee exposures under the performance option may be used to demonstrate that employee exposure to silica will remain below the AL of 25 μg/m³ measured as an 8-hour TWA under any foreseeable conditions for purposes of ascertaining coverage under paragraph (a)(2). Objective data, such as an employer's historical air monitoring data, reflecting "worst case" conditions, in particular, may be helpful in characterizing exposures for purposes of determining coverage under the standard.

When employers rely on objective data generated by others as an alternative to developing their own air monitoring data, they remain responsible for ensuring that the data relied upon accurately characterize each employee's current exposures.

An employer may characterize employee exposures within a range. For example, an employer following the performance option could determine that an employee is exposed below the AL or between the AL and the PEL. See 81 Fed. Reg. at 16763. An employer using the performance option could also determine that exposures exceed the PEL by a certain level, such as less than 10 times the PEL. In addition, an employer using the performance option could characterize exposures using a "worst-case" assessment of the highest exposure levels expected during an employee's workday. OSHA notes that employers must reassess exposures when a change occurs that could reasonably be expected to result in new or additional exposures at or above the AL. See 29 C.F.R. § 1910.1053(d)(4).

Yes. Old sampling data, or historical air monitoring data, may qualify as "objective data" if the data demonstrate employee exposure to silica associated with a particular product or material or a specific process, task, or activity. Like all objective data, old sampling data can be used to assess current exposures only if the data 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. See 29 C.F.R. § 1910.1053(b). Any historical air monitoring data (or other objective data) an employer uses to meet its exposure assessment obligations under the performance option must, alone or in combination with other objective data, enable the employer to accurately characterize employee exposures. See 29 C.F.R. § 1910.1053(d)(2). Employers must characterize employees' exposure as an 8-hour TWA in micrograms per cubic meter of air (μg/m³).

Yes. Data generated by real-time monitoring of respirable dust levels (conducted using direct-reading instruments) can be combined with exposure mapping to assess employee exposures under the performance option, provided that the data can be correlated with individual employee exposures and otherwise meet the requirements for objective data. OSHA notes that in order to estimate the level of respirable crystalline silica in the air using real-time monitoring data, employers must also know the percentage of silica in the dust (e.g., from the analysis of a bulk sample or information from a safety data sheet). If an employer does not know the percentage of silica in the dust, it can assume 100% of the respirable dust is silica for purposes of determining worst case exposures from real-time monitoring data under the standard.

The goal of the performance option is to give employers flexibility to accurately characterize employee exposures using whatever combination of air monitoring data or objective data is most appropriate for their circumstances. Therefore, OSHA has not specified exactly how often data should be collected for these purposes. Employers may rely on existing data as long as the data continues to be sufficient to accurately characterize employee exposures. OSHA notes, however, that accurately characterizing employee exposures is an ongoing duty, and employers must 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 AL, or when the employer has any reason to believe that new or additional exposures at or above the AL have occurred. See 29 C.F.R. § 1910.1053(d)(4).

OSHA has not specified or recommended a particular number of testing locations or positions. If an employer chooses to characterize exposures using area samples or other exposure mapping approaches, it must determine which testing locations or positions will provide it with the data needed to accurately characterize the exposure of each employee. See 29 C.F.R. § 1910.1053(d)(2). Care must be taken when extrapolating data from area samples or other exposure mapping approaches to avoid mischaracterizing an employee's personal TWA exposure.

Yes, provided that the requirements in the standard are met. First, the data must meet the definition of "objective data." Specifically, the data must demonstrate employee exposure to silica associated with a particular product or material or a specific process, task, or activity, and 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. See 29 C.F.R. § 1910.1053(b). Objective data could be, for example, air monitoring data developed by an industry trade association based on standard products and processes in that industry. Second, the data must be sufficient to accurately characterize employee exposures to silica at the specific worksite. See 29 C.F.R. § 1910.1053(d)(2).

In order to determine whether the data meet these requirements, an evaluation of silica-generating tasks must be performed by each employer at each facility. This evaluation would generally involve determining whether the conditions under which the objective data were generated are similar enough to, or have a higher exposure potential than, the conditions at the employer's worksite such that the data "accurately characterize" exposures for each employee performing the tasks in question. Employers that rely on objective data generated by others are responsible for ensuring that the data relied upon accurately characterize their own employees' exposures. And employers must keep records of any objective data used to characterize their employees' exposures, in accordance with paragraph (k)(2).

Yes. The duty to assess employee exposures under the performance option is ongoing. There is no set schedule for reassessment of exposures under the performance option. However, in order for an employer to continue to accurately characterize its employees' exposures, reassessment must occur 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 AL, or when the employer has any reason to believe that new or additional exposures at or above the AL have occurred. See 29 C.F.R. § 1910.1053(d)(4). For example, reassessment would be required if the flow rate of the employer's ventilation system decreases. Not all changes in the workplace, however, will trigger the reassessment requirement. For example, reassessment would not be required if a personnel change is made that is not expected to impact the magnitude of employee exposure to silica.

If an employer wants to minimize the frequency with which it needs to reassess employee silica exposures, the employer can, at the outset, characterize exposures within a range, e.g., between the AL and the PEL, or using the worst case (or highest exposure) scenario.

It depends. Under the performance option, objective data may be used to characterize employee exposures when that data reflects 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. See 29 C.F.R. § 1910.1053(b). If the workplace conditions under which product A is produced are the same or have a higher exposure potential than the conditions that will exist when product B is produced, then the employer could reasonably determine that the exposure information generated based on product A can be used to characterize exposures for the days when product B is produced. In order to make this determination, the employer must consider the processes, types of material, control methods, work practices, and environmental conditions that exist when producing both products, The employer must be able to demonstrate that, in both cases, the employee exposure information relied upon is sufficient to accurately characterize exposures under paragraph (d)(2).

An employer using the scheduled monitoring option must reassess employee 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 AL, or when the employer has any reason to believe that new or additional exposures at or above the AL have occurred. See 29 C.F.R. § 1910.1053(d)(4). If an employer has performed exposure monitoring when the facility is producing product A, and plans to switch production to product B, the employer will need to determine if any changes made as a result of the change in product are reasonably expected to result in new or additional silica exposures at or above the AL. If such new or additional exposures are reasonably expected, the employer must perform additional monitoring during production of product B. If new or additional exposures above the AL are not reasonably expected, the employer may rely on the sampling data collected during production of product A.

No. Employers using the scheduled monitoring option must 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. But, where several employees perform the same tasks on the same shift and in the same work area, employers may sample a representative fraction of these employees in order to meet this requirement. Representative sampling involves monitoring the employee or employees reasonably expected to have the highest exposure (for example, the employee closest to an exposure source). See 29 C.F.R. § 1910.1053(d)(3)(i). This exposure is then assigned to the other employees in the group who perform the same tasks on the same shift and in the same work area.

Employers should remember that the general industry standard requires employers to individually notify each affected employee in writing of the results of the exposure assessment or post the assessment results in an appropriate location accessible to all affected employees. See 29 C.F.R. § 1910.1053(d)(6)(i). The term "affected" includes all employees whose exposures were assessed, even those employees whose exposures were determined by representative sampling of other employees.

The silica standard does not prohibit employers from requiring employees to wear personal samplers as a condition of employment, however, other state or federal laws or regulations, or collective bargaining agreements, may apply. OSHA notes that the standard does not require employers to sample every employee at each worksite. For example, under the scheduled monitoring option, employers may use representative sampling to assess the exposure of employees. See 29 C.F.R. § 1910.1053(d)(3)(i).

No. However, employers must make and maintain accurate records of all exposure measurements taken to assess employee exposure and all objective data relied upon to comply with the standard. See 29 C.F.R. § 1910.1053(k)(1), (2). These records must be provided to OSHA upon request. See 29 C.F.R. § 1910.1020(e)(3)(i).

Considering the SAE associated with employers' air sampling results can enhance employers' understanding of exposures that occur in their workplaces by providing an indication of the extent to which random measurement error can affect sampling results. Employers considering the SAE reported by their labs should, however, consider both the lower and upper ends of the range of exposures described using the SAE. Employers can be confident that a measured exposure is below the PEL if the sum of the sampling result and the result times the SAE is below the PEL. For example, an employer that receives a sample result of 40 μg/m³ with a reported SAE of 18 percent can be confident that the exposure is below the PEL because the upper end of the exposure range is below 50 μg/m³ (i.e., 40 + (40 x .18) = 47.2). However, where requirements of the standard are triggered by exposure levels (i.e., the AL or the PEL), these requirements are triggered by the measured exposure level, without regard to SAE.

OSHA uses its own SAE (i.e., the SAE calculated by OSHA's lab) in its enforcement of PELs, including the silica PEL. The sample result being analyzed by OSHA's lab must exceed the PEL by more than the PEL multiplied by the SAE to be considered an overexposure (see Section II, Chapter 1, IV.D of the OSHA Technical Manual, https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html). For example, given the silica PEL of 50 μg/m³ and assuming an SAE of 17 percent, an air sample result would have to be greater than 58.5 μg/m³ (i.e., 50 + (50 x 0.17)) to be considered to have exceeded the PEL. This policy gives employers the benefit of the doubt because it assumes that a sample result that is above the PEL, but below the PEL adjusted for the SAE (i.e., PEL + (PEL x SAE)), is not a violation of the standard. OSHA does not cite an employer for a violation of the exposure limit unless the Agency has obtained a sample measurement that is above the PEL after accounting for SAE.

No. The silica standard does not require records of air monitoring data to include employees’ social security numbers. OSHA previously required social security numbers on these records because social security numbers, which do not change over time, are unique and constant personal identifiers that offer a useful method for linking records with individual employees. However, recognizing the threat of identity theft and the availability of other methods for tracking employees for research purposes, OSHA published a final rule that removed the requirements for employers to include employee social security numbers on exposure monitoring, medical surveillance, and other records from most of OSHA’s health standards, including the silica standard. See 84 Fed. Reg. 21416 (May 14, 2019).

No. Paragraph (d)(6)(i) of the standard requires employers to notify affected employees of exposure assessment results. Employers can do so either by individually notifying each affected employee of the results in writing or by posting the results in an appropriate location accessible to all affected employees. If an employer chooses to notify employees by posting the results, the employer can use any employee identification method that ensures affected workers can identify their results, e.g., by using the employees' names, identification numbers, or specific job titles and work shifts.

If an employer conducts exposure monitoring to assess employee exposures, the period for employee notification of assessment results does not begin to run until the employer receives the monitoring results.

No. The term "regulated area" is defined as an area where an employee's silica exposure exceeds, or can reasonably be expected to exceed, the PEL. See 29 C.F.R. § 1910.1053(b). If an employer has, and adequately enforces, work rules precluding employees from entering a particular area, then the employer does not need to treat that location as a regulated area. Furthermore, an area does not need to be designated as a regulated area if the employer has and enforces work rules limiting employees' time in the area so that there is no reasonable expectation that their 8-hour TWA exposures will exceed the PEL. OSHA notes, however, that if one or more employees will enter the area long enough that it is reasonable to expect their 8-hour TWA exposures to exceed the PEL, the employer must establish a regulated area and all employees entering the area must wear respirators (even those not in the area long enough for their exposures to exceed the PEL). See 29 C.F.R. § 1910.1053(e)(4).

No. In some facilities, exposures above the PEL may be associated with an intermittent activity. Employers do not need to treat an area as a regulated area on days when employee exposures are not reasonably expected to exceed the PEL. In such cases, employers may elect to demarcate the regulated area on a temporary basis, on days when exposures are reasonably expected to exceed the PEL, by means of movable stanchions, portable cones, or barricade tape, as long as the required warning sign with prescribed hazard language is posted at all entrances. See 29 C.F.R. § 1910.1053(e)(2), (j)(2).

Employers must demarcate (mark off) regulated areas from the rest of the workplace in a manner that minimizes the number of employees exposed to silica within those areas. See 29 C.F.R. § 1910.1053(e)(2)(i). However, the standard does not require a specific method of demarcation. Employers can determine how to demarcate regulated areas based on their knowledge of the specific conditions of their workplaces. Traffic cones, stanchions, tape, barricades, lines, or textured flooring may all be effective means of demarcating the boundaries of regulated areas. In determining how to demarcate regulated areas, employers may consider factors such as the configuration of the area, whether the regulated area is permanent, the airborne respirable crystalline silica concentration, the number of employees in adjacent areas, and the period of time the area is expected to have exposure levels above the PEL.

Employers must also post signs at all entrances to regulated areas that bear the legend specified in paragraph (j)(2) of the standard:

DANGER
RESPIRABLE CRYSTALLINE SILICA
MAY CAUSE CANCER
CAUSES DAMAGE TO LUNGS
WEAR RESPIRATORY PROTECTION IN THIS AREA
AUTHORIZED PERSONNEL ONLY.

See 29 C.F.R. § 1910.1053(e)(2)(ii). The purpose of these signs, which supplement the training employees receive under other provisions of the standard, is to minimize the number of employees in a regulated area by alerting them that they must be authorized to enter, and to ensure that employees take appropriate protective measures when entering.

Because there is an exposure above the PEL, the facility must determine which task or operation is creating the overexposure and create a regulated area around that task or operation. In the example provided, the regulated area may include only the first employee's work station. If the second employee is not exposed above the PEL and is not reasonably expected to be exposed above the PEL, the regulated area does not have to cover that employee's work area. An employer could choose to use area sampling, real-time monitoring, or exposure mapping to assist in identifying the boundaries of a regulated area.

Signs bearing all of the specific cautionary wording specified in the standard must be posted at entrances to all regulated areas. See 29 C.F.R. § 1910.1053(e)(2)(ii). Thus, the signs must say: "DANGER – RESPIRABLE CRYSTALLINE SILICA – MAY CAUSE CANCER – CAUSES DAMAGE TO LUNGS – WEAR RESPIRATORY PROTECTION IN THIS AREA – AUTHORIZED PERSONNEL ONLY." 29 C.F.R. § 1910.1053(j)(2). Additional words or information may be included on the sign provided that the additional material is not confusing or misleading and does not detract from the language required by the standard. For example, employers may choose to include information about other silica-related health hazards, e.g., kidney damage, or a heading at the top of the sign designed to draw workers' attention, e.g., "Notice for Employees" or "Worker Alert."

Yes. Administrative controls, which are a type of work practice control, are an acceptable means of reducing employee exposures under 29 C.F.R. § 1910.1053(f)(1). For example, an employer could schedule high-exposure tasks to be conducted when employees are not working in adjacent areas. The standard does not prohibit the rotation of employees (a type of administrative control) to limit employee exposures. However, OSHA discourages this practice as a means of avoiding implementation of engineering and other work practice controls. It can be administratively difficult to maintain employees' exposures at or below the PEL solely using rotation. Moreover, the use of rotation may require the employer to provide medical surveillance to additional workers and to train many workers on multiple jobs.

No. Paragraph (f)(1) requires employers to use feasible engineering and work practice controls to reduce and maintain exposures to or below the PEL. If the use of engineering and work practice controls results in exposures at or below the PEL, the employer need not use additional controls (even if feasible) to lower exposures further (i.e., to an even lower level). On the other hand, if exposures are above the PEL, but the employer can demonstrate that it has implemented all feasible engineering and work practice controls, then the employer is in compliance with paragraph (f)(1) (assuming the provision and use of required respiratory protection in accordance with paragraph (g)).

No. Tasks that are not covered by the standard, e.g., because the employer has objective data demonstrating that employee exposures will remain below the AL under any foreseeable conditions, do not need to be included in the written exposure control plan.

The written exposure control plan must describe the tasks that involve silica exposures in sufficient detail to enable the employer and employees to consistently identify and control silica-related hazards. See 29 C.F.R. § 1910.1053(f)(2)(i)(A); 81 Fed. Reg. at 16800-1. Thus, for example, if the materials being disturbed or the conditions under which the tasks are performed are relevant to the level of exposure related to the particular task, that information must be included. Employers may develop a single comprehensive plan for each worksite that includes all of the silica-generating tasks that employees will perform at the worksite (i.e., employers do not need separate exposure control plans for different operations, processes, or shifts at the same worksite). However, using a broad term that could describe multiple tasks, such as "foundry operations" or "manufacturing," would not be sufficiently descriptive.

Note that in addition to describing the silica-generating tasks, the exposure control plan must also include a description of the engineering controls, work practices, and respiratory protection used to limit exposure to respirable crystalline silica. See 29 C.F.R. § 1910.1053(f)(2)(i)(B).

No. The standard requires employers to review and evaluate the effectiveness of the written exposure control plan at least annually, and to update it as necessary, because work conditions can change (e.g., the employer purchases a new type of equipment). However, the standard does not require that the review and evaluation be in writing or documented. Any updates to the plan adopted as a result of the review will need to be documented by incorporation in the written plan, and employers may document the review and evaluation process as a best practice. Retaining such documentation can help employers verify that they have reviewed and evaluated the plan, as required.

No, none of the standard's requirements apply if the employer has objective data demonstrating that exposures will remain below the AL under any foreseeable conditions. Employers should note, however, that dry sweeping, dry brushing, and the use of compressed air, either alone or in combination with other tasks, can result in exposures at or above the AL. Employers should consider the duration of the dry sweeping, dry brushing, or use of compressed air; the location and frequency of the tasks; and other factors in developing objective data to demonstrate that employee exposures will remain below the AL under any foreseeable conditions. (Note that the standard's housekeeping provisions apply in areas where dry sweeping, dry brushing, or the use of compressed air could contribute to the exposures of any employees who are covered by the standard.)

When these types of sweepers are equipped with HEPA filters, and effectively remove dirt and dust, their use is considered "HEPA-filtered vacuuming" for purposes of paragraph (h)(1) of the standard, and they are not prohibited by the rule. When these types of sweepers are not equipped with HEPA filters, their use is considered an "other [housekeeping] method[]," and they are not prohibited by the standard's housekeeping provisions, as long as they are operated and maintained properly so as to minimize the likelihood of employee exposure. See 29 C.F.R. § 1910.1053(h)(1).

For all such sweepers (HEPA or non-HEPA), the employer using the sweeper must ensure compliance with all applicable provisions of the silica standard, including the PEL. Thus, the employer must assess the exposures of employees operating or working in the vicinity of the sweeper in accordance with paragraph (d) of the standard. And if any of those employees are exposed to silica levels above the PEL, the employer must use feasible engineering and work practice controls to reduce and maintain each employee's exposure to or below the PEL in accordance with paragraphs (c) and (f)(1) of the standard. Such controls could include appropriate modifications to the sweepers (e.g., installing a shroud around the bottom of the equipment to limit escaping dust) or establishing new, appropriate work practices. If feasible engineering and work practice controls are not sufficient to reduce exposures to or below the PEL, the employer must use them to reduce employee exposure to the lowest feasible level and provide appropriate respiratory protection that complies with the requirements of paragraph (g). See 29 C.F.R. § 1910.1053(f)(1).

OSHA encourages employers to acquire industrial sweepers equipped with HEPA filters when their existing sweepers need to be replaced.

The standard does not require employers to demonstrate that wet methods, a HEPA-filtered vacuum, or other methods are impossible to use in order to establish "infeasibility" for purposes of paragraph (h). As explained in the preamble to the standard, the limited "infeasibility" exceptions included in these housekeeping provisions are intended to encompass situations where wet methods, HEPA-filtered vacuuming, and other exposure-minimizing methods are not effective, would cause damage, or would create a hazard in the workplace. See 81 Fed. Reg. at 16795-96. For example, an employer can establish infeasibility for these purposes by demonstrating that wet sweeping, using a HEPA-filtered vacuum, and other methods that minimize the likelihood of exposure would negatively impact the quality of the work being done. However, even in cases where one of the acceptable cleaning methods may not be feasible, employers may be able to use another acceptable cleaning method. Irrespective of the housekeeping method used, employers must always assess and limit the silica exposures of employees, as required by paragraphs (c) and (d)(1).

No. The proper use of commercially-available dust-suppression sweeping compounds in accordance with the manufacturer's instructions is a cleaning "method[] that minimize[s] the likelihood of exposure" for purposes of paragraph (h)(1). Thus, it is an acceptable housekeeping method under the standard.

Yes, provided the compound is used properly and effectively suppresses the generation of respirable crystalline silica dust during dry sweeping or dry brushing.

OSHA considers this wet sweeping, permitted under the housekeeping provisions of the standard, as long as the dust is still wet when it is swept.

No. Shoveling is not considered dry sweeping, regardless of the type or amount of material being shoveled, and is not subject to the restrictions on dry sweeping in the standard. Instead, employers would need to assess exposures and follow the hierarchy of controls to reduce and maintain exposures to or below the PEL, as required by paragraphs (c) and (d)(1).

No. The standard generally prohibits the use of compressed air "to clean clothing or surfaces" where that activity can contribute to employee silica exposures. 29 C.F.R. § 1910.1053(h)(2). It does not prohibit the use of compressed air for purposes other than cleaning clothing or surfaces, e.g., for operating a pneumatic tool. Employers may also use compressed air for housekeeping purposes when the compressed air is used in conjunction with a ventilation system that effectively captures the dust cloud created by the compressed air, or if no alternative method for cleaning clothes or surfaces is feasible. See 29 C.F.R. § 1910.1053(h)(2)(i), (ii). When the standard permits the use of compressed air, and the employer does not have objective data demonstrating that the employee exposures resulting from the use of compressed air will remain below the AL under any foreseeable conditions, the employer must comply with exposure control requirements and other applicable provisions of the standard.

The standard does not specify the use of a particular ventilation system for these purposes. Whatever type of system is selected, it must be able to effectively capture any dust cloud created by the use of compressed air, thereby preventing the dust cloud from entering employees' breathing zones and contributing to silica exposures. For example, in the preamble to the standard, OSHA noted that the use of clothes-cleaning booths would be permitted because although such booths use compressed air to clean clothes, the dust is "blown out of the employee's breathing zone and is captured by a filter." 81 Fed. Reg. at 16797.

No. The general industry standard does not require vacuums to be equipped with HEPA filters. However, when vacuums are used without HEPA filtration, they may contribute to employee silica exposures. Employers should consider any such exposures for purposes of compliance with all of the provisions of the standard. For example, if fugitive dust from non-HEPA-filtered vacuuming or other discharge from vacuums contributes to employee exposures that exceed the PEL, then the employer would need to follow the hierarchy of controls to reduce and maintain exposures to or below the PEL. In such situations, employers might consider fitting vacuums with HEPA filters or using vacuum systems that discharge outside the facility.

The answer to both questions is no. The standard does not prohibit the use of a vacuum to remove silica dust from employees' clothes (e.g., before employees leave the worksite for lunch or at the end of their shift), nor does it require vacuums to be equipped with HEPA filters. However, when vacuums without HEPA filtration are used to clean clothing, they may contribute to employee silica exposures. Employers should consider any such exposures for purposes of compliance with all of the provisions of the standard. For example, if fugitive dust from non-HEPA-filtered vacuuming or other discharge from vacuums contributes to employee exposures that exceed the PEL, then the employer would need to follow the hierarchy of controls to reduce and maintain exposures to or below the PEL. In such situations, employers might consider fitting vacuums with HEPA filters or using vacuum systems that discharge outside the facility.

No. With some exceptions, the standard prohibits the use of compressed air for cleaning clothing and surfaces. It does not address compressed air exhausted from hand-held tools. However, employers should remember to consider any exposures created by the exhausted air to ensure compliance with all provisions of the standard. For example, if the exhausted air contributes to silica exposures that exceed the PEL, the employer would need to follow the hierarchy of controls to reduce and maintain exposures to or below the PEL. See 29 C.F.R. § 1910.1053(f)(1).

No. For initial and periodic examinations, employers may choose to use any health care provider that meets the definition of a PLHCP in paragraph (b) of the standard, including a qualified in-house health care professional. Similarly, if an additional examination by a specialist is required by 29 C.F.R. § 1910.1053(i)(7), an employer with a specialist on staff may elect to have the additional examination(s) performed by that in-house physician. Employers must ensure that in-house PLHCPs, like all PLHCPs performing medical surveillance examinations and procedures under the silica standard, adhere to the standard's confidentiality requirements. See 29 C.F.R. § 1910.1053(i)(6)(ii), (7)(iv).

Yes, the silica standard permits employers to select a health care professional to perform the medical examinations required by the standard. Employers must ensure that all the medical examinations required by the standard are performed by a PLHCP, i.e., "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 (i)." 29 C.F.R. § 1910.1053(b), see also 29 C.F.R. § 1910.1053(i)(1)(ii). Employers should consult state or local laws for relevant requirements.

No, although the standard requires employers to make medical surveillance available to qualifying employees, the standard does not require qualifying employees to participate in medical surveillance. However, the employer must offer the examination fairly and in good faith, at no cost to employees, and at a reasonable time and place, and must make another examination available if the employee requests it, or, at a minimum, the next time an examination is due (i.e., within three years). See 29 C.F.R. § 1910.1053(i). In addition, the standard requires employers to train employees on the purpose of the medical surveillance program. See 29 C.F.R. § 1910.1053(j)(3)(i)(E). If an employer wishes to document an employee's decision to decline a medical examination, the employer could ask the employee to sign a statement affirming that he or she was offered the benefits and declined to participate.

Note that the medical examination under the silica standard is different than the medical evaluations required under the respiratory protection standard. If an employee declines a medical evaluation under the respiratory protection standard, then the employer may not assign him or her a task requiring respirator use.

Nothing in the silica standard precludes an employer from requiring participation in medical surveillance programs, as appropriate under other applicable laws or collective bargaining agreements.

No. The standard limits only the information that can be included in the PLHCP's or specialist's written medical opinion for the employer following an examination offered to an employee for purposes of compliance with the medical surveillance provisions of the standard. If an employer uses the same individual or entity to manage medical surveillance and workers' compensation records, there must be separate procedures for maintaining and managing the separate sources of information.

The standard does not preclude employers from offering employees a second medical surveillance examination that meets the requirements of paragraph (i). However, if any of the written medical opinions provided to the employer as a result of the first or subsequent medical surveillance examinations contains a statement that the employee should be examined by a specialist, or a statement that the employee should receive more frequent periodic examinations, then the employer must make the required examination(s) available, in accordance with 29 C.F.R. § 1910.1053(i)(7) or (i)(3), respectively. Any second examination must also be provided at a reasonable time and place and at no cost to the employee, and the restrictions on information that can be provided to the employer without the employee's authorization would apply equally to the second written medical opinion.

No. The standard requires the employer to make available an additional examination with a specialist only if the PLHCP's written medical opinion for the employer indicates that the employee should be examined by a specialist. See 29 C.F.R. § 1910.1053(i)(7)(i). And the employee must provide written authorization before the PLHCP's written medical opinion for the employer may include a recommendation for a specialist examination. See 29 C.F.R. § 1910.1053(i)(6)(ii)(B). Thus, if the PLHCP's opinion for the employer does not contain the PLHCP's recommendation for a specialist examination because the employee did not authorize the employer to receive it, then the employer is not responsible for offering additional examinations. See 81 Fed. Reg. at 16837.

Among other things, OSHA's respiratory protection standard requires employers to provide a medical evaluation to determine the employee's ability to use a respirator, before the employee is fit tested or required to use the respirator in the workplace. See 29 C.F.R. § 1910.134(e)(1). It also requires employers to obtain a written recommendation from the PLHCP on whether the employee is medically able to use a respirator. See 29 C.F.R. § 1910.134(e)(6)(i)(A). If an employee receives medical surveillance under the silica standard, the PLHCP's written medical opinion for the employer also must include any recommended limitations on the employee's use of respirators. See 29 C.F.R. § 1910.1053(i)(6)(i)(C). If a PLHCP determines through either a medical evaluation under the respiratory protection standard, or medical surveillance under the silica standard, that an employee has a medical condition that places the employee's health at increased risk if a negative pressure respirator is used, but the employee can use a powered air purifying respirator (PAPR), then the employer must provide a PAPR. See 29 C.F.R. § 1910.134(e)(6)(ii). OSHA believes many workers who are medically unable to use a negative pressure respirator will be able to use a PAPR. However, if an employee cannot use either type of respirator, then the employer must not assign the employee to perform a task that would require the employee to use a respirator. In such a situation, the employer may need to consult other local, state, or federal laws and regulations and collective bargaining agreements to determine its obligations with respect to such employees.

No. Employers are in the best position to determine how training can most effectively be accomplished. Therefore, the standard does not specify how an employer needs to train employees. Acceptable forms of training may include hands-on training, videos, slide presentations, classroom instruction, informal discussions during safety meetings, written materials, or any combination of these methods. However, to ensure that employees comprehend the material presented during training, it is critical that trainees have the opportunity to ask questions and receive answers if they do not fully understand the material presented to them. This requirement can be met in a variety of ways. For example, employers that train employees through video presentations or computer-based programs can have a qualified trainer available to address questions after the presentation, or provide a telephone hotline so that trainees have direct access to a qualified trainer. See 81 Fed. Reg. at 16845. Employers may also choose to designate a qualified employee to answer questions for these purposes.

There is no set method employers must use to ensure employees demonstrate knowledge and understanding of the required subjects. Instead, the standard defines employers' training obligations in terms of performance-oriented objectives meant to ensure that employees are aware of the hazards associated with silica in their workplace and how they can help protect themselves. However, as a general matter, employers can determine whether employees have the requisite knowledge through methods such as discussion of the required training subjects, written tests, or oral quizzes. See 81 Fed. Reg. at 16845.

The requirement for training is performance-oriented in order to allow flexibility for employers to provide training as needed to ensure that each employee can demonstrate the knowledge and understanding required under the rule. Although the standard does not set a fixed schedule for periodic training, additional or repeated training may be necessary under certain circumstances. For example, if an employer observes an employee engaging in activities that contradict knowledge gained through training, it is a sign to the employer that the employee may require a reminder or periodic retraining on work practices. See 81 Fed. Reg. at 16850.

The training requirements in paragraph (j)(3) apply only to employees who fall within the scope of the silica standard. See 29 C.F.R. § 1910.1053(j)(3)(i). However, the hazard communication standard, which includes requirements for hazard communication training, applies to hazardous chemicals (including respirable crystalline silica) regardless of the airborne exposure level. See 29 C.F.R. §§ 1910.1053(j)(1), 1910.1200.

Employers are responsible for maintaining records in their possession (e.g., the PLHCP's written medical opinion for the employer described in paragraph (i)(6)). Employers are also responsible for ensuring the retention of records in the possession of the PLHCP (e.g., the written medical report for the employee described in paragraph (i)(5)). An employer can fulfill this second obligation by including the retention requirement in a written agreement between the employer and the PLHCP or by otherwise specifically communicating to the PLHCP the substance of OSHA's record-retention requirements. See 81 Fed. Reg. at 16854.

Yes. Temporary workers are entitled to the same protections as other employees under the Occupational Safety and Health Act and OSHA health and safety standards. Therefore, temporary workers within the scope of the silica standard must be protected as required by the standard. The duration of employment does not matter, except that the requirement for medical surveillance is triggered only for employees who will be occupationally exposed to silica at or above a threshold level for 30 or more days per year (see question 63, below).

When a staffing agency supplies temporary workers to a business, the staffing agency and the staffing agency's client (the host employer) must coordinate to ensure that the temporary workers are fully protected by the standard. While the host employer is often better situated to assess hazards and protect temporary workers from silica-related hazards in the workplace, the staffing agency may be better positioned to offer other protections under the silica standard, such as general training and medical surveillance.

Yes, host employers must ensure that the exposures of temporary workers who are or may reasonably be expected to be exposed to silica at or above the AL are assessed using either the performance option in paragraph (d)(2) or the scheduled monitoring option in paragraph (d)(3). Host employers using the performance option may rely on the same objective and/or air monitoring data used to assess the exposures of permanent employees, as long as such data accurately characterize the exposures of the temporary workers. See 29 C.F.R. § 1910.1053(d)(2). Host employers using the scheduled monitoring option may rely upon representative sampling to assess the exposures of temporary workers when the temporary workers are performing the same tasks on the same shift and in the same work area as the employees whose exposures have been sampled. (Representative sampling involves sampling the employees expected to have the highest silica exposures.) See 29 C.F.R. § 1910.1053(d)(3)(i).

Yes. In accordance with paragraphs (c) and (f) of the silica standard, host employers must ensure that temporary workers are not exposed to silica above the PEL, using the hierarchy of controls set forth in the standard. Where respiratory protection is required, the host employer and the staffing agency can reach agreement as to which employer will provide and pay for the respirators.

Yes. Host employers must ensure that temporary workers who enter regulated areas use appropriate respiratory protection, in accordance with paragraphs (e)(4) and (g) of the standard, as well as 29 C.F.R. § 1910.134. Although the host employer is often better situated to assess and control workplace hazards than the staffing agency that supplies the temporary workers, the staffing agency and the host employer may agree to have the staffing agency provide the temporary workers with respirators, as well as medical evaluations and fit testing required for respirator use, in accordance with 29 C.F.R. § 1910.134.

It depends. A host employer has no obligation to make medical surveillance available to temporary workers who will not be exposed at or above the AL (or, before June 23, 2020, above the PEL) for 30 or more days in a 12-month period while working for the host employer. If a worker will be exposed above the appropriate trigger for medical surveillance for 30 or more days in a 12-month period at the host site, and the worker has not had a medical examination that meets the requirements of the silica standard within the last three years, then the host employer must work with the staffing agency to make sure the worker is offered medical surveillance. The staffing agency must determine the total days of exposure at or above the AL (or, before June 23, 2020, above the PEL) during all periods of employment with all host employers within each 12-month period and must add those days together to determine whether medical surveillance must be made available to a temporary worker.

Under paragraph (j) of the silica standard, host employers must ensure that temporary workers are trained and can demonstrate knowledge and understanding of the topics listed in that paragraph. Staffing agencies may be well-positioned to offer workers some of the general training required under paragraph (j) of the standard. However, some worksite-specific training is always required, and host employers are generally better situated to provide training on worksite-specific job tasks, machinery, equipment, processes, and measures taken to protect workers. OSHA recommends that staffing agencies and host employers coordinate responsibilities for the various aspects of silica-related training and inform each other when they have fulfilled their respective training obligations. For more complete information, see https://www.osha.gov/Publications/OSHA3859.pdf.