Exposure to crystalline silica can cause a variety of lung diseases, including silicosis, lung cancer, COPD (chronic obstructive pulmonary disease), decreased lung function, increased likelihood of getting tuberculosis, and immune system and kidney effects. Although most cases of silicosis develop after years of exposure, instances of extremely high exposure have resulted in illness and even death in a matter of weeks.
The 8-hour permissible exposure limit (PEL) for airborne crystalline silica is established at 0.05 mg/m3 with an Action Level of 0.025 mg/m3 (see Table AC-1 of 5155 and section 1532.3).
Hazardous work activities include abrasive blasting with sand and loading, dumping, chipping, hammering, cutting, and drilling of rock, sand, or concrete. Generally, during work on materials, such as rock or concrete that contain a significant amount of silica, continuous exposure to a visible cloud of dust will probably result in levels of exposure that exceed the PELs. However, in some cases the PELs can be exceeded even when there is no visible cloud of dust.
For additional information on the hazards and control of silica exposures see the:
Hazards of Silica in Construction eTool (www.dir.ca.gov/dosh/etools/08-019/index.htm)
Respirable Crystalline Silica Standards Update and FAQ (www.dir.ca.gov/dosh/respiratory-silica- FAQ.html).