Respirable crystalline silica is now the most actively litigated occupational exposure in the country, driving both a wave of OSHA enforcement under the 2016 standards and a fast-growing body of product-liability and toxic-tort claims arising from engineered-stone fabrication. In each forum the outcome turns on the same technical questions: what was measured, how it was measured, and whether the exposure record can bear the legal weight placed on it. This paper explains where a qualified safety and industrial hygiene expert changes the analysis — for the agency, the employer, the plaintiff, and the defense alike.