Exposure to crystalline silica can cause a variety of lung diseases including silicosis, lung cancer, COPD (chronic obstructive pulmonary disease), decreased lung function, and increased likelihood of getting tuberculosis.
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. Airborne permissible exposure limits (PELs) are established for several different forms of crystalline silica. These limits range from 0.05 to 0.1 mg/m3 of respirable dust, expressed as an 8hour TWA (see Table AC-1 of 5155).
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 (20% or greater), 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).
Before beginning work that could expose employees to crystalline silica, employers must comply with the following requirements detailed in Step 4 through 6 below.