​NIOSH Finds Silica Overexposures during Dirt Road Maintenance

During a recent health hazard evaluation (HHE), NIOSH staff found that some employees working to maintain dirt roads for a federal government agency had silica exposures above occupational exposure limits. The HHE was requested by a management representative who was concerned about potential exposures to erionite mineral fibers when employees worked on dirt roads in areas where the mineral was suspected to be present. According to the HHE report, exposure to erionite fibers is associated with health effects similar to those typically seen with asbestos exposure. 

NIOSH investigators visited two work areas to assess potential employee exposures to erionite fibers and, because of the dusty nature of the work, respirable crystalline silica. Agency staff members took air samples for the mineral fibers and crystalline silica, and took bulk rock and soil samples to analyze for erionite. NIOSH found that the road maintenance activities disturbed dust that contained crystalline silica, and that area air samples indicated a high percentage of quartz—up to 100 percent. However, no air or bulk samples contained erionite.
The report lists several recommendations to improve workers’ health and safety, including:
  • maintain equipment filters regularly as recommended by the manufacturers
  • conduct full-shift personal air sampling for respirable crystalline silica
  • wet soil or aggregate before disturbing it to reduce dust generation
  • provide employees with respiratory protection if follow-up monitoring shows overexposures to crystalline silica
View NIOSH’s full report.
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