F1: Research Roundup Exposure Assessment

The Mine Safety and Health Administration (MSHA) finalized a rule to enhance protections for miners against respirable crystalline silica, a known health hazard linked to severe illnesses. The rule, titled "Lowering Miners' Exposure to Respirable Crystalline Silica and Improving Respiratory Protection," updates outdated standards to align with current occupational health practices and the OSHA requirements for General Industry and Construction. The MSHA silica rule introduces a uniform permissible exposure limit (PEL) of 50 micrograms per cubic meter (µg/m³) for an 8-hour time-weighted average across all mining sectors, replacing varied limits based on mine type. An action level of 25 µg/m³ triggers additional monitoring. Operators must implement feasible engineering controls, supplemented by administrative controls, to maintain exposures below the PEL or provide miners with respiratory protection if that is infeasible. The rule addresses a critical health issue, as silica exposure contributes to a 400% increase in lung transplants for black lung disease since 2016, with 1 in 5 Appalachian miners affected.

This study discusses the sampling issues with methods that provide an acceptable ISO compliant respirable sample, appropriate choice of sampling train, the affects of humidity and the interference of other materials not covered by the standard in the ore body. We will also cover some logistical issues with mining overloading analytic labs to comply with the standard. 

Metal additive manufacturing is transforming industry but introduces unique occupational health risks. Although the laser powder bed fusion process is enclosed, exposures can occur during powder handling, cleaning, and post-processing.

This case study presents three industrial hygiene evaluations at facilities using nickel, cobalt, chromium, and titanium-based alloys. Personal and area air monitoring, metal profiling, and particulate logging were performed under worst-case conditions. At one facility, exposures were below OSHA limits, but nickel exceeded ACGIH thresholds for technicians who vacuumed parts and machines during the workday. At a second facility, a technician who hand-sieved powders exposure exceeded OELs for nickel, cobalt, and iron. Key lessons emphasize the impact of work practices, the effectiveness of HVAC filtration, and the importance of respiratory protection in controlling risk and safeguarding worker health.