Why did OSHA issue a new crystalline silica rule?

OSHA’s previous permissible exposure limits (PELs) for silica were outdated, inconsistent and did not adequately protect worker health. The previous PELs were based on studies from the 1960s and earlier that did not reflect more recent scientific evidence showing that low-level exposures to silica cause serious health effects, including lung cancer. In the 45 years since the previous PELs were established, the U.S. National Toxicology Program, the International Agency for Research on Cancer, and the National Institute for Occupational Safety and Health have all identified respirable crystalline silica as a human carcinogen. Previous construction and shipyard PELs were based on an old method of measuring worker exposures to silica that is not used today. Those previous limits are inconsistent, allowing permissible levels for construction and shipyards to be more than twice as high as levels in general industry. The revised rule will reduce the risk of disease among workers who inhale respirable crystalline silica and provide the same protection for all workers covered.