Toxic and hazardous substances: Silica - California

California operates an OSHA-approved State Plan covering most private sector workers and all state and local government workers. The California Code of Regulations and Division of Occupational Safety and Health (Cal/OSHA) has the following additional requirements:

Employers covered by Section 5204 must:

1. Determine if “high-exposure trigger tasks” are performed at the workplace.
   1. High-exposure trigger tasks include machining, crushing, cutting, grinding, drilling, or polishing of artificial stone that contains more than 0.1% by weight crystalline silica, or other silica-containing products, including natural stone, that contain more than 10% by weight crystalline silica.
   2. High-exposure trigger tasks also include clean up, disturbing, or handling of wastes, dusts, residues, debris, or other materials created during the above-listed tasks.
2. If employees perform high-exposure trigger tasks, do all of the following regardless of employee exposure levels:
   1. Determine employee exposures: Have a qualified person1 measure employee exposures to respirable crystalline silica at least once every 12 months. Exposures must be below the Permissible Exposure Limit (PEL) of 50 µg/m3 of air, measured over eight hours. However, because silica dust is so dangerous, employers must comply with all worker protections for high-exposure trigger tasks, even if exposure measurements are under 50 µg/m3.
   2. Establish a regulated area: A regulated area is an area demarcated from the rest of the workplace. Regulated areas are established to limit the number of employees exposed to respirable crystalline silica.
      1. Ensure that only authorized persons with the correct protective equipment enter the regulated area.
      2. Conduct all high-exposure trigger tasks and other work with silica exposures within regulated areas.
   3. Use effective wet methods at all times.
      1. Water must cover the entire surface of the stone slab whenever a tool, piece of equipment, or machine contacts the stone. Please see further details in the description of engineering controls below.
   4. Clean up dusts, debris, and residues frequently to prevent the accumulation of dust on surfaces.
      1. Use only wet methods or vacuums with HEPA2 filters for all cleaning.
   5. Prohibitions:
      1. Prohibit dry cleaning and sweeping, dry brushing, and use of compressed air.
      2. Prohibit walking through or moving equipment through dust, debris, or residue.
   6. Use required respiratory protection at all times.
      1. Ensure all employees who perform or work near high-exposure trigger tasks wear a powered air purifying respirator (PAPR) or another respirator with an assigned protection factor of 1000 or better.
      2. Ensure that employees are medically cleared to use a respirator.
      3. Ensure that employees are properly fitted and trained to use a respirator.
      4. Provide a full-face, tight-fitting positive-pressure, supplied-air respirator to employees with confirmed or suspected silicosis.
3. For workplaces with employee exposure to respirable crystalline silica, including workplaces with high-exposure trigger tasks and those without high-exposure trigger tasks, do all of the following:
   1. Use a qualified person to assess employee exposures to ensure exposures are below the Permissible Exposure Limit (PEL) of 50 micrograms of respirable crystalline silica per cubic meter of air, measured over eight hours.
      1. Notify all employees of the results of exposure assessments. 2 “High-Efficiency Particulate Air (HEPA) Filter” means a filter that is at least 99.97 percent efficient in removing mono-dispersed particles of 0.3 micrometers in diameter.
   2. Use engineering controls and safe work practices to maintain employee exposures below the PEL.
      1. Engineering controls that an employer can use include:
         1. Substitution. Use a material that has a low silica content, such as marble or limestone, instead of artificial stone.
         2. Isolation. Use automated machines in enclosed areas separated from workers.
         3. Barriers. Use physical barriers or partitions to separate cutting, grinding, or polishing areas from other parts of the workplace to prevent the spread of silica dust.
         4. Wet methods (required at all times for high-exposure trigger tasks). Ensure water covers the entire surface of the stone slab where a tool, piece of equipment, or machine contacts the stone. Water that is recycled must be filtered to remove silica. Use one or a combination of the following wet methods:
            1. Sheet-wetting, which forms a continuous flow of water over the surface of the work object.
            2. Tools with built-in water application systems, such as saws, grinders, chippers and polishers.
            3. Water-jet cutters.
            4. Wet milling machines and wet stone routers.
            5. Automated machines with built-in water application.
         5. Ventilation. Use local exhaust ventilation to remove silica dust from the air at the point where the tool or equipment contacts the stone and before the dust enters the worker’s breathing zone. Exhausted air must go through a HEPA filter to remove respirable crystalline silica.
      2. Safe work practices include:
         1. Training employees to perform tasks and use tools, water systems, and ventilation in a way that prevents dust exposures.
         2. Scheduling work so that high-exposure tasks are performed when fewer or no other employees are in the regulated area.
         3. Cleaning work areas frequently using wet methods or HEPA-filtered vacuums to prevent re-suspension of silica dust.
         4. Ensuring that employees do not take breaks, eat, or drink in regulated areas or other areas where silica dust could be present.
         5. Ensuring that employees frequently clean their clothes and protective equipment to remove dust, including before breaks, drinking, or eating.
         6. Ensuring that employees clean their clothes and protective equipment with a HEPA vacuum or wet methods.
         7. Prohibiting the use of compressed air or dry brushing for any purpose.
         8. Ensuring that employees remove protective equipment and wash their hands and face before breaks, drinking, eating, or leaving the workplace.
      3. Post signs at all entrances to regulated areas.
      4. Provide employees with information and training.
      5. Provide medical exams with specific tests to employees exposed to respirable crystalline silica.
      6. Provide Medical Removal Benefits.
         1. Remove an employee from silica exposure when recommended by the PLHCP, and maintain the employee’s earnings, seniority, and benefits for up to six months, with certain exceptions.
      7. Report silicosis and lung cancer cases within 24 hours to Cal/OSHA and the California Department of Public Health.
      8. Establish a written exposure control plan.
      9. Maintain records.
         1. Develop and maintain an accurate record of all exposure measurements taken to assess employee exposure to silica.
         2. Subsection (n) of Section 5204 requires employers to document specific types of information in the exposure record.