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The performance option is useful when measuring employee exposures is challenging, such as when tasks are conducted for short durations of time or performed under different weather conditions.
The performance option gives employers flexibility to determine the 8-hour TWA exposure for each employee based on any combination of air monitoring data or objective data that can accurately characterize employee exposures to silica.
Air monitoring data are any results of air monitoring that the employer has done to meet the requirements of the standard.
Objective data is information that demonstrates employee exposure to silica associated with a particular product or material or a specific process, task, or activity.
The data must reflect workplace conditions that closely resemble or could result in higher exposures than the processes, types of material, control methods, work practices, and environmental conditions in the employer’s current operations.
Examples of objective data are information such as:
- Air monitoring data from industry-wide surveys,
- Calculations based on the composition of a substance,
- Area sampling results and exposure mapping profile approaches, and
- Historic air monitoring data.
- Conduct the exposure assessment before work begins;
- Reassess exposures whenever a change in production, process, control equipment, personnel, or work practices may reasonably be expected to result in new or higher 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;
- Be able to demonstrate that employee exposures have been accurately characterized; and
- Make sure that the exposure assessment reflects the exposures of employees on each shift, for each job classification, in each work area.
Employers must make and keep an accurate record of all:
- Air monitoring performed,
- Objective data, and
- Medical surveillance.