The Occupational Safety and Health Administration’s new proposed regulation to reduce workplace exposure to crystalline silica has been almost 40 years in the making. Also called silicon dioxide (or, more commonly, quartz), crystalline silica occurs abundantly in sand, soil, and rock. OSHA first established a maximum permissible exposure level for crystalline silica in 1970 by adopting a consensus industry standard. Unfortunately, the form of that standard was obsolete by the time it was adopted, and OSHA issued an advance notice of proposed rulemaking to modify it in 1974, but took no further action. Then, in 1994 OSHA identified crystalline silica as one of a few top priority safety and health hazards, and, two years later, the International Agency for Research on Cancer concluded that “crystalline silica inhaled in the form of quartz or cristobalite from occupational sources is carcinogenic to humans.” In 1998, OSHA listed regulation of silica on its semi-annual agenda of upcoming regulatory actions and, by the fall of 1999, set itself a deadline of June 2000 for issuing a proposed rule. In 2002, OSHA revised the deadline to November 2003 and listed the proposed rule as one of its top priorities. This deadline kept slipping, however, until February 2011, when OSHA sent a draft of the rule to the Office of Information and Regulatory Affairs for interagency review. This review took an unusually-long two-and-a-half years to complete, but culminated in OSHA publishing a proposal on its website on August 23, 2013.