Crystalline silica is an abundant natural material found in soil, stone and sand. It is also present in many construction materials such as brick, mortar and concrete. It becomes respirable when any of the afore-mentioned materials are cut or broken down into fine particles.
Typical activities that can create silica dust or respirable crystalline silica include blasting, chipping, cutting, grinding and drilling. More than 85 percent of workers exposed to respirable crystalline silica work in the construction industry. Other industries where workers are exposed include: asphalt roofing materials, concrete products, cut stone, dental laboratories, foundries, jewelry, porcelain enameling, pottery, railroads, ready-mix concrete, shipyards, structural clay products, and support activities for oil and gas operations.