According to Donald Elswick, CIH, CSP, CHMM, CET, an Ohio safety professional who consults to manufacturers: “The new U.S. OSHA Final Rule on Respirable Crystalline Silica sets a lower permissible exposure level (PEL) of 50 μg/m3 for all industries covered by the rule, adopts the more conservative ISO/CEN criteria of a 4-um cut-point for respirable dust samplers, and allows any sampler conforming to ISO 7708/CEN criteria to be used.” In this short whitepaper, Elswick discusses the utility of Parallel Particle Impactor (PPI) respirable dust samplers in providing objective data to measure the new action level of 25 μg/m3, calculated as an 8-hour total weight average (TWA). Exposures at or above the action level will trigger requirements for exposure assessment, should the rule take effect as scheduled on June 23, 2018. 11/30/2017