Crystalline silica is found in many construction materials, including concrete, stone, and brick masonry.  The inhalation of silica dust is thought to contribute to the formation of many health hazards, including lung cancer, silicosis, COPD, and kidney disease.  Estimates have shown that silica exposure kills 600 American workers and results in 900 new cases of silicosis each year,  OSHA has been working on tightening its rules regarding the exposure to this type of dust for several years and has finally issued a new “final rule,” it’s first update on the rule since 1971.