Silica Hazards Information

Dangers of Silica - Silica may be of several distinct types. For example, quartz is a crystalline form of silica and is the most common mineral in the earth's crust. When rock containing quartz is chipped, hammered, drilled, crushed, loaded, hauled, or dumped, small particles of silica are released into the air and can be inhaled by workers.

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Worker Information Cards - PDF Format - Adobe Acrobat Reader Required
Health hazard information cards, Crystalline Silica Exposure, will help workers and employers understand more about how they can protect themselves against exposure to silica dust. Two separate cards, available in English and Spanish, provide a quick reference and recommendations for construction and general industry

Silica Card for Construction - English

Silica Card for Construction - Spanish

Silica Card for General Industry - English

Silica Card for General Industry - Spanish

Technical Information
    Silica - Silicosis

Power Point
    Silica Hazards

 

Silica Work Practices - procedures followed by both employers and workers to control silica hazards in the workplace. Examples of work practices are

—wet drilling or sawing of silica-containing materials,
—showering and changing into clean clothing before leaving work, and
—avoiding smoking, eating, and drinking in dusty areas.

Silica Respiratory protection  - prevents workers from inhaling pollutants. Appropriate respiratory protection equipment and programs should be provided whenever engineering controls and work practices cannot keep concentrations of airborne silica at or below safe limits.

Respirators—Workers can wear special protective equipment called respirators to protect them from inhaling respirable crystalline silica. Respirators are a good option as protective equipment, but they should be used only when controls (such as substitution, automation, enclosed systems, and local exhaust ventilation) cannot keep exposures at or below safe limits.

Workers who perform sandblasting must use the type of respirator recommended by NIOSH for their particular job. Regardless of the abrasive used, NIOSH recommends a respirator that provides a constant supply of clean air through a line that connects to a hood or helmet worn by the worker. The respirator air line must be separate from the line that supplies air for blasting. This device is known as a type CE abrasive-blasting respirator operated in the continuous-flow mode.

Respiratory Protection Program—To make sure that respirators are used properly, the employer must establish a comprehensive respiratory protection program as required in the OSHA respiratory protection standard of 1998 (see the NIOSH Guide to Industrial Respiratory Protection for guidance).

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Silica sand containing quartz is used in sandblasting equipment to clean surfaces. The outsides of buildings and bridges and the insides of storage tanks and pipes are some of the surfaces that are cleaned by sandblasting.

The silica sand used in sandblasting breaks into fine particles that stay in the air. If these particles are small enough to be inhaled deeply into the lungs, they are known as respirable crystalline silica. Inhaling these fine silica particles causes more lung damage than inhaling larger particles. This process causes rapid and severe forms of silicosis in sandblasters.

Silicosis - When workers inhale crystalline silica, the lung develops scar tissue around the silica particles. This process results in a lung disease known as silicosis. As more lung tissue is damaged by silica dust, breathing becomes more difficult, chest pain occurs, and death may result. Silicosis patients suffer shortness of breath, fever, and cyanosis. Some patients are diagnosed incorrectly as having pulmonary edema, pneumonia, or other lung diseases.

Preventing Silica Exposure
Industrial hygiene practices are used to protect workers from silicosis and other workplace hazards. These practices include the use of substitution, engineering controls, work practices, respiratory protection, and air monitoring. Employers are responsible for implementing these practices when they are needed to provide safe and healthful workplaces.
 

Substitution -  Several abrasive agents may be used as substitutes for silica sand during sandblasting. Some of the abrasives studied are steel grit, specular hematite, nickel slag, copper slag, crushed glass, garnet, staurolite, olivine, and coal slag. Most of these abrasives work as well as silica sand and cost about the same or even less. However, the use of a substitute may have other adverse effects. Regardless of the type of abrasive, the use of engineering controls, work practices, respiratory protection, and air monitoring to reduce hazards to workers during sandblasting is necessary.

Engineering Controls - Engineering controls are hazard controls designed into equipment and workplaces. Examples of engineering controls are

—automated equipment operated from an enclosed booth,
—enclosed blast-cleaning machines and cabinets,
—tools with dust collection systems, and
—local exhaust ventilation.