exposure level (PEL) for respirable dust containing crystalline silica is determined by calculating the maximum respirable dust concentration permissible in the worker’s breathing zone based on the percent of free silica present. The higher the percentage of free silica presents in the sample, the lower the permissible exposure level to respirable dust.

Part IV:

The National Institute of Occupational Safety and Health recommends the following measures be taken to reduce exposures to respirable crystalline silica.

  1. Recognize when silica dust may be generated and plan ahead to eliminate or control the dust at the source. Awareness and planning are keys to the prevention of silicosis.
  2. Do not use silica sand or other substances containing more than 1 percent crystalline silica as abrasive blasting materials. Substitute less hazardous materials.
  3. Use engineering and administrative controls and containment methods to control the hazard and protect adjacent workers from exposures (e.g., local exhaust ventilation, wet methods, blast-cleaning machines and cabinets, etc.).
  4. Routinely maintain dust control systems to keep them in good working order.
  5. Practice good personal hygiene to avoid unnecessary exposure to other worksite contaminants, such as lead.
  6. Wear disposable or washable protective clothes at the worksite.
  7. Shower (if possible) and change into clean clothes before leaving the worksite to prevent contamination of cars, homes, and other work areas.
  8. Conduct air monitoring to measure worker exposures to respirable crystalline silica and ensure that controls are providing adequate protection to workers.
  9. Provide periodic medical examinations for all workers who may be exposed to respirable crystalline silica.
  10. Post warning signs to mark the boundaries of work areas contaminated with respirable crystalline silica.
  11. Report all cases of silicosis to OSHA.

240