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OSHA Has Answers for Silica Rule FAQs

Recent interpretations of some provisions provide guidance for employers.

Ever since the U.S. Occupational Health and Safety Administration (OSHA) began enforcing its respirable crystalline silica standard for general industry in June 2018, employers have had questions about it. On Jan. 23, OSHA published a list of Frequently Asked Questions (FAQs) and answers developed in consultation with industry and union stakeholders.

“The FAQs provide important interpretations of several of the provisions in the rule and provide employers with additional flexibility for compliance,” observes attorney Bradford T. Hammock of the law firm of Littler Mendelson, who provided a summary of some of the most important questions and answers provided by OSHA.

The silica standard establishes a permissible exposure limit (PEL) of 50 μg/m3 as an eight-hour time-weighted average (TWA), and an action level of 25 μg/m3, calculated as an eight-hour TWA. Employers must ensure that employees are not exposed to respirable crystalline silica (RCS) above the PEL.

Employers must perform exposure assessments of each employee who is or may reasonably be expected to be exposed to RCS at or above the action level, and provide medical surveillance for employees who are exposed to RCS at or above the action level for 30 or more days per year. Employers also must establish regulated areas and provide respiratory protection, housekeeping, training, hazard communication and medical surveillance.

The silica standard does not apply to agricultural operators, exposures that result from the processing of sorptive clays, or construction work. OSHA published separate FAQs for the construction industry in August 2018.

The standard also does not apply to employers who have objective data demonstrating that employee exposure will remain below the action level under foreseeable conditions, Hammock points out.

OSHA considers the failure of most controls to be a foreseeable condition and thus employers should consider this when making their assessments. However, OSHA states that failure of some types of controls (e.g., substitution of non-silica-containing materials, fixed walls) 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 coverage.

In determining whether the standard applies, employers also don’t need to disable, remove or otherwise account for the potential failure of measures that may contribute in a limited way to reducing silica exposures but which are not adopted for that specific purpose, such as general building ventilation or HVAC systems.

Clarifying Exposure Prevention

Employers must ensure no employee is exposed to an airborne concentration of silica in excess of the PEL. Employers must assess the exposure of each employee who is exposed to respirable crystalline silica at or above the Action Level (AL) using either a performance option or a scheduled monitoring option. This includes the option of switching from the scheduled monitoring option to the performance option, and can make use of air monitoring data generated during scheduled monitoring to fulfill the performance option assessment requirements.

The term “objective data” means information demonstrating employee exposure to silica associated with a particular product or material or a specific process, task or activity. Data that may qualify include industry-wide surveys; information from equipment manufacturers or trade associations; exposure mapping; calculations based on substance composition or chemical and physical properties; and historical air monitoring data.

Employers don’t have to sample every employee if using the scheduled monitoring option. 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, OSHA says. Although employers are not banned from requiring employees to wear personal samplers as a condition of employment under the standard, other laws, regulations or collective bargaining agreements may apply.

Employers must demarcate regulated areas from the rest of the workplace and post signs with a specified legend at all entrances to those areas. Access to regulated areas must be limited and require the use of a respirator for each person who enters it. A regulated area does not need to be demarcated if the employer enforces work rules limiting employees’ time in it so there is no reasonable expectation that their eight-hour TWA exposures will exceed the PEL.

When it comes to intermittent activity, employers don’t have to create a regulated area on days when employee exposures are not reasonably expected to exceed the PEL. In such cases, OSHA says employers may demarcate the regulated area on just a temporary basis.

Administrative controls are an acceptable means of reducing employee exposures. An employer could reduce an employee’s exposures by scheduling high-exposure tasks to be conducted when that employee is not working in an adjacent area. Rotation of employees to limit employee exposures also is not prohibited.

Tasks that are not covered by the standard—such as when the employer has objective data demonstrating that employee exposures will remain below the AL—do not need to be included in the written exposure control plan required under the standard.

Employers also are allowed to develop a single comprehensive plan for each worksite that includes all of the silica-generating tasks that employees will perform at the worksite. In other words, they don’t need separate exposure control plans for different operations.

If an employer has objective data demonstrating that employee exposure will remain below the AL under any foreseeable conditions, the prohibition on dry sweeping, dry brushing and the use of compressed air for cleaning clothing and surfaces does not apply.

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,” OSHA notes. Infeasibility exceptions 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.

This information, of course, represents just a portion of the clarifications offered by OSHA in its FAQs. Other topics covered include hazard communication, recordkeeping, temporary employees and more. The full silica FAQs are available on the agency’s website.


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