Option 3 – Review the Published Data
The following is a sample of published data on the silica content of selected common building materials. Although the list is not comprehensive, it provides one more indicator to help a user decide if a material contains silica.
| Percent of Silica Content HSE (1) | Examples of the Silica Content of Select Building Materials Amount of Crystalline Silica (quartz) Queensland (2) | |
|---|---|---|
| Brick | Up to 30% | 15% - 27% |
| Calcium-silicate bricks | 50% - 55% | |
| Concrete, cement, mortar | 25% - 70% | |
| Aggregate in concrete | 30% | |
| Fiber cement sheets | 10% - 30% | |
| Tile | 30% - 45% | |
| Sandstone, gritstone, quartzite | More than 70% | |
| Sand, gravel, flint | 96% - 100% | |
| Granite | Up to 30% | |
| Slate | Up to 40% | |
| Flint | More than 80% | |
| Demolition dust | 3% - 4% |
(1) Source: Great Britain’s Health and Safety Executive, which is responsible for “securing the health, safety and welfare of people at work” and protecting “others from risks to health and safety from work activity,” compiled the figures for silica-containing materials.
(2) Source: Workplace Health and Safety Queensland, Department of Justice and Attorney-General Silicosis and the lung.
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It is important to keep in mind that it only takes a very small amount of airborne silica dust to create a health hazard. These dust particles are very small. You cannot see them. For illustrative purposes, at a national conference on silica hazards and prevention in the late 1990s, the Director of NIOSH said that “NIOSH’s recommended exposure level to silica was equivalent to no more than a teaspoon of dust in a football field…” Or as this picture shows – over a normal workday, a worker should not be exposed to an amount greater than this pinch of dust (the equivalent of the NIOSH Recommended Exposure Limit of 0.05 mg/m3 and assuming the worker breathed 10 m3 over an 8 hour shift.)
Photo courtesy of Dr. Geoff Plumlee, USGS
