This chapter applies to all occupational exposures to respirable crystalline silica, except for the following:

1. (1) Where employee exposure results from the processing of sorptive clays.
2. (2) Where documented objective data demonstrates that employee exposures to respirable crystalline silica will remain below 25 micrograms per cubic meter of air (25 μg/m3) as an 8-hour TWA under any foreseeable conditions.

[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060 and chapter 49.17 RCW. WSR 18-07-098, § 296-840-100, filed 3/20/18, effective 4/23/18.]