This section applies to all occupational exposures except for tasks performed according to the requirements in WAC 296-840-110.

(1) Permissible exposure limit (PEL). You must ensure that no employee is exposed to an airborne concentration of respirable crystalline silica in excess of the 8-hour TWA.

(2) Exposure assessment. You must 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 (a) of this subsection or the scheduled monitoring option in (b) of this subsection.

(a) Performance option. You must assess the 8-hour TWA 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.

(b) Scheduled monitoring option:

(i) You must perform initial monitoring to assess the 8-hour TWA for each employee on the basis of personal breathing zone air samples that reflect the exposures of employees on each shift, for each job classification, in each work area.

(ii) Where several employees perform the same tasks on the same shift and in the same work area, you may sample a representative fraction of these employees in order to meet this requirement.

(iii) In representative sampling, you must sample the employee(s) who are expected to have the highest exposure to respirable crystalline silica.

(iv) If initial monitoring indicates that employee exposures are below the action level, you may discontinue monitoring for those employees whose exposures are represented by such monitoring.

(v) Where the most recent exposure monitoring indicates that employee exposures are at or above the action level but at or below the PEL, you must repeat such monitoring within six months of the most recent monitoring.

(vi) 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.

(vii) Where the most recent (noninitial) exposure monitoring indicates that employee exposures are below the action level, you must 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 subsection (3) of this section.

(3) Reassessment of exposures. You 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 action level, or when the employer has any reason to believe that new or additional exposures at or above the action level have occurred.

(4) Methods of sample analysis. You must ensure that all samples taken to satisfy the monitoring requirements of subsection (2) of this section are evaluated by a laboratory that analyzes air samples for respirable crystalline silica in accordance with the procedures in WAC 296-840-165 Appendix A—Methods of sample analysis of this chapter.

(5) Employee notification of assessment results.

(a) 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 in accordance with the following:

(i) Construction employers must notify affected employees within five working days after receiving any results of an exposure assessment in accordance with this rule.

(ii) All other employers must notify affected employees within fifteen working days after receiving any results of an exposure assessment in accordance with this rule.

(b) Whenever an exposure assessment indicates that employee exposure is above the PEL, you must describe in the written notification the corrective action being taken to reduce employee exposure to or below the PEL.

(6) Observation of monitoring.

(a) Where air monitoring is performed to comply with the requirements of this chapter, you must provide affected employees or their designated representatives an opportunity to observe any monitoring of employee exposure to respirable crystalline silica.

(b) When observation of monitoring requires entry into an area where the use of protective clothing or equipment is required for any workplace hazard, you must provide the observer with protective clothing and equipment at no cost and shall ensure that the observer uses such clothing and equipment.