What is silica?

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by Rudi Nieuwoudt 

As safety professionals I am sure that most of you have heard the term Silica and that this substance holds some potential health risks if not kept in check. But how many of us actually know what the whole Silica risk is all about? If you have never heard of silica before, you might be surprised to hear that you probably come into contact with it every day. Silica makes up the mineral called quartz, and it is the most abundant mineral in the earth's crust. It is the main component of most sand and the primary ingredient in glass. Every time you pick up a glass to take a drink, you are using silica.

Silica has been known to humans since ancient times, long before we knew it was made of silicon and oxygen. The art of making glass objects with silica dates back centuries. Today, there are many industrial uses for silica. These include abrasives, building materials, fillers, electronics, and water filtration. 

So when is Silica hazardous to my health?

Materials that contain crystalline silica are not hazardous unless they are disturbed, generating small-sized particles that can get in your lungs (“respirable crystalline silica”).  For example, blasting, cutting, chipping, drilling and grinding materials that contain silica can result in silica dust that is hazardous for construction workers and others to breathe.

Where am I likely to encounter hazardous forms of Silica?

  • Asphalt (for paving)
  • Brick
  • Cement
  • Concrete
  • Concrete Blocks
  • Fiber Cement products
  • Drywall
  • Grout 
  • Mortar
  • Gunite/Shotcrete
  • Plaster
  • Paints containing silica
  • Refractory Mortar/Castables
  • Rock
  • Refractory Units
  • Sand
  • Roofing tiles & pavers
  • Stone (including: granite, limestone, quartzite, sandstone, shale, slate, cultured, etc.)
  • Soil (fill dirt and top soil)
  • Stucco/EIFS
  • Tiles 

What tasks are likely to release hazardous silica?

  • Abrasive blasting  
  • Cutting/sawing
  • Demolishing/disturbing 
  • Drilling
  • Earth Moving
  • Frac sand cleanup
  • Frac sand mixing
  • Frac sand offloading
  • Frac sand onloading
  • Grinding
  • Jackhammering
  • Milling
  • Mixing
  • Polishing
  • Sandblasting
  • Scabbling
  • Scarifying
  • Sweeping
  • Scraping

What are the effects of silica on the human body?

1. Silicosis, a disabling, not-reversible and sometimes fatal lung disease
2. Other non-malignant respiratory diseases, such as chronic bronchitis
3. Lung cancer
4. Kidney disease, including nephritis and end-stage renal disease
5. Possible auto-immune disorders
6. Possible cardiovascular disease

What controls may be used to protect yourself from silica exposure?

‍1. Do not bypass, disable or misuse engineering controls such as blasting cabinets, water sprays, and local exhaust ventilation systems.
2. Always use the correct respirator and eye protection when silica dust is present
3. Never alter a respirator or use a respirator that does not fit or function properly
4. Apply water to silica dust producing material when cutting, sawing, drilling or crushing it, to reduce dust volumes
5. Take extra precautions to avoid silica when working in construction, concrete, foundry, abrasive blasting, painting, coating, glass, pottery, or rock yard atmospheres
6. Minimize the buildup of silica dust as much as possible
7. Avoid eating, drinking, using tobacco products, and applying cosmetics in areas where silica dust is present
8. Always wash hands and face before eating drinking, smoking, or applying cosmetics outside of the exposure area