Silica
About 2.3 million workers are exposed to respirable crystalline silica in their workplaces, including 2 million construction workers who drill, cut, crush, or grind silica-containing materials such as concrete and stone, and 300,000 workers in general industry operations such as brick manufacturing, foundries, and hydraulic fracturing, also known as fracking.
Quartz is the most common form of crystalline silica. In fact, it is the second most common surface material accounting for almost 12% by volume of the earth's crust. Quartz is present in many materials in the construction industry, such as brick and mortar, concrete, slate, dimensional stone (granite, sandstone), stone aggregate, tile, and sand used for blasting. Other construction materials that contain crystalline silica are asphalt filler, roofing granules, plastic composites, soils, and to a lesser extent, some wallboard joint compounds, paint, plaster, caulking and putty.
Exposure to excessive silica dust causes lung scarring and disease over time. The size of the airborne silica particles determines the amount of risk. Smaller particles can be inhaled deep into the lungs where they can cause damage. Larger particles, such as beach sand, are not as great a concern because they are too large to inhale.
Compressed Air

Brick Cutting

Concrete Cutting

Check out this short audio clip by Dan Clark of the theSafetyBrief.com. Silica dust is common in worksites, can scar the lungs and cause cancer. Symptoms sometimes don't appear for 10 years.
Knowledge Check Choose the best answer for the question.
1-7. Exposure to excessive silica dust causes _____ over time.
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