Protecting Workers from Silica Dust: A Guide to Exposure Assessment and Control
Assessing Silica Dust Exposure in the Workplace
About 2.3 million people in the U.S. are exposed to silica at work. Assessing worker exposure to respirable crystalline silica is important to determine the need for exposure controls and personal protective equipment. Prior to exposure monitoring, review each analytical method carefully and consult an accredited laboratory for analysis.
What is Silica Dust?
Silica (SiO2) is a naturally occurring widely abundant mineral that forms the major component of most rocks and soils. There are non-crystalline and crystalline forms of silicon dioxide. In dry form, only fine Crystalline silica constitutes a toxic respirable dust hazard, since its inhalation as airborne dust could give rise to silicosis. The non-crystalline form of silica does not cause this kind of lung damage.
Crystalline silica is a common mineral found in the earth's crust. Materials like sand, stone, concrete, and mortar contain crystalline silica. It is also used to make products such as glass, pottery, ceramics, bricks, and artificial stone.
What can cause Silica Dust?
Respirable crystalline silica – very small particles at least 100 times smaller than ordinary sand you might find on beaches and playgrounds – is created when cutting, sawing, grinding, drilling, and crushing stone, rock, concrete, brick, block, and mortar. Activities such as abrasive blasting with sand; sawing brick or concrete; sanding or drilling into concrete walls; grinding mortar; manufacturing brick, concrete blocks, stone countertops, or ceramic products; and cutting or crushing stone result in worker exposures to respirable crystalline silica dust. Industrial sand used in certain operations, such as foundry work and hydraulic fracturing (fracking), is also a source of respirable crystalline silica exposure.
The Dangers of Silica Dust Exposure
Silica dust is harmful when inhaled into your lungs. As it is 100 times smaller than a grain of sand, you can be breathing it in without knowing.
Exposure to silica dust can lead to the development of lung cancer, silicosis (an irreversible scarring and stiffening of the lungs), kidney disease and chronic obstructive pulmonary disease.
An estimated 230 people develop lung cancer each year as a result of past exposure to silica dust at work. Not all exposed workers will develop cancer; cancer risk increases with long-term or repeated high-level exposure.
Workers who inhale these very small crystalline silica particles are at increased risk of developing serious silica-related diseases, including:
- Silicosis, an incurable lung disease that can lead to disability and death;
- Lung cancer;
- Chronic obstructive pulmonary disease (COPD)
- Kidney disease
Protecting Workers from Silica-Related Diseases
To protect workers exposed to respirable crystalline silica, OSHA has issued two respirable crystalline silica standards: one for construction, and the other for general industry and maritime.
For construction workers, employers must limit exposures and take steps to protect their workers (standard 29 CFR 1926.1153), such as using water or vacuums to prevent dust in the air.
For maritime workers, protecting workers can include limiting access to areas above the permissible exposure limit (PEL), training workers, improved housekeeping methods, offering medical exams, and more.