OSHA proposes to halve and harmonize silica exposure thresholds

Sources: Occupational Safety and Health Administration; CP staff

In Notice of Proposed Rulemaking (NPRM) for Occupational Exposure to Respirable Crystalline Silica, OSHA outlines reduction of permissible exposure limits (PEL) for quartz from current general industry and construction thresholds—100 and 250 micrograms per cubic meter of air (μg/m3) expressed in eight-hour weighted averages, respectively—to a uniform 50 μg/m3.

The document was announced August 23, a 90-day public comment period opening upon pending publication in the Federal Register. Agency officials note that PELs for respirable crystalline silica in general industry and construction have not been updated since their adoption in 1971, shortly after OSHA’s creation, while the quartz PEL in construction is a “formula based on a now-obsolete particle count sampling method that is approximately equivalent to 250 μg/m3.”

Inspectors currently enforce PELs that agency officials view as “outdated, inconsistent between industries and not adequately protect[ing] worker health. The proposed rule brings protections into the 21st century.”

OSHA proposes the rule with the aim of “curbing lung cancer, silicosis, chronic obstructive pulmonary disease and kidney disease in America’s workers.”

“Exposure to silica can be deadly, and limiting that exposure is essential,” said Dr. David Michaels, assistant secretary of labor for occupational safety and health. “Every year, exposed workers not only lose their ability to work, but also to breathe. This proposal is expected to prevent thousands of deaths. [It] uses common sense measures that will protect workers’ lives and lungs—like keeping the material wet so dust doesn’t become airborne, [and] is designed to give employers flexibility in selecting ways to meet the standard.”

Once full effects are realized, OSHA estimates that the proposed rule will result in saving nearly 700 lives and prevent 1,600 new cases of silicosis annually. Its proposal is based on review of scientific and technical evidence, consideration of current industry consensus standards and outreach by OSHA to stakeholders, including public stakeholder meetings, conferences and meetings with employer and employee organizations.