Silica
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Summary The hazard: Silica is found in sandstone, granite, flint, and slate and other common materials. Silicosis and acute silicosis are lung diseases that can cause death or disability as the result of breathing silica particles. Who is at risk: Workers exposed to dust containing silica during highway construction, sand blasting, loading and hauling or crushing rocks, cutting or grinding or chipping stone, demolition or concrete or masonry structures. Prevention: Avoid using products that contain silica if possible, keep dust out of the air with wet methods and/or ventilation, and wear respirators and protective clothing. Laws: The Occupational Safety and Health Administration (OSHA) permissible exposure limit is 10 milligrams (ten one-thousandths of a gram) of silica per cubic meter of air (10 mg/m3) averaged over an 8-hour work shift, or no more than a total of 30 milligrams of silica per cubic meter of air (30 mg/m3) over an 8-hour shift. |
What is silica?
Silica is found in sandstone, granite, flint, and slate and other common materials.
What are the health effects of silica?
Silica causes disease when workers breathe in tiny silica particles that are released from rocks and ores. The particles are so small they can only be seen with a microscope.
- Silicosis is a disease that develops over time (chronic) resulting in disability or death. Scar tissue forms in the lungs around the silica particles that are inhaled, making it hard to breathe. Silicosis also increases the risk of other lung diseases, such as tuberculosis, and may lead to heart failure or lung cancer.
- Acute silicosis causes death or severe lung damage. This disease develops rapidly when workers breathe in large amounts of very fine crystalline silica.
Who is at risk?
AFSCME members who are exposed to dust that contains silica include those involved in:
- highway construction, rock drilling, masonry, jack hammering, excavations, and tunneling,
- crushing, loading, hauling and dumping of rock,
- sandblasting or blasting with abrasive containing silica,
- stone cutting, grinding, or chipping, and
- demolition of concrete or masonry structures.
What can be done to protect workers?
- Do not use silica-containing materials for abrasive blasting. Use other products that contain glass beads, pumice, steel grit, or walnut shells.
- Determine ahead of time if rocks or earth are likely to contain silica.
- Control dust by using wet drilling and sawing methods (wet processes), blast-cleaning machines and cabinets, and enclosed cabs on earth moving heavy equipment.
- Keep equipment in good working order.
- Conduct regular air-monitoring to measure silica levels in the work area.
- Use respirators when other control methods cannot keep the silica exposures below safe levels. Use type CE positive pressure abrasive blast respirators when sandblasting.
- Change into disposable or washable clothes at the worksite Shower and change before leaving the worksite. Do not take contaminated clothes home!
- Do not eat, drink, or use tobacco products in or near dusty areas, and always wash up before eating, drinking, or smoking.
What laws are there to protect workers?
The Occupational Safety and Health Administration (OSHA) has legal limits on workers' exposure to certain toxic substances. The OSHA limit is called a permissible exposure limit (PEL). The OSHA permissible exposure limit is 10 milligrams (a milligram is one-thousandth of a gram) of silica per cubic meter of air (10 mg/m3) averaged over an 8-hour work shift. In addition, workers cannot be exposed to more than a total of 30 milligrams of silica per cubic meter of air (30 mg/m3) over an 8-hour shift.
The National Institute for Occupational Safety and Health (NIOSH) has more information about silica and other occupational hazards. To contact NIOSH, call 1-800-35-NIOSH or go to the NIOSH web site. NIOSH has a recommended exposure limit that is much lower than the OSHA permissible exposure limit. NIOSH recommends that worker exposure be less than 50 millionths of a gram per cubic meter of air (0.05 mg/m3) for up to a 10-hour workday, or 40-hour workweek.
January 2001
For more information about protecting workers from workplace hazards, contact the AFSCME Health and Safety Program at (202) 429-1228, or 1625 L Street, N.W., Washington, DC 20036.