Protecting Workers From Silica Exposure

Silicosis, one of the oldest occupational diseases, still kills thousands of people every year, everywhere in the world, according to the World Health Organization. It is an incurable lung disease caused by inhalation of dust containing free crystalline silica. It is irreversible and, moreover, the disease progresses even when exposure stops.

The most severe exposures to crystalline silica result from sandblasting, which may be done to clean sand and irregularities from foundry castings, finish tombstones, etch or frost glass, or remove paint, oils, rust, or dirt from objects that will be repainted or treated. Other exposures to dust from sand occur in cement manufacturing, asphalt pavement manufacturing and the foundry industry. Crystalline silica is used in the electronics industry and in manufacturing abrasives, paints, soaps and glass. Calcined diatomaceous earth, which can contain crystalline silica, is used for filtration in food and beverage production. Work in mines, quarries, foundries, and construction sites, in the manufacture of glass, ceramics, and abrasive powders, and in masonry workshops is particularly risky.

OSHA has established a Permissible Exposure Limit (PEL) which is the maximum amount of airborne crystalline silica that an employee maybe exposed to during the work shift. OSHA is also beginning a Special Emphasis Program to inform employers and employees about the occurrence and hazards of crystalline silica and ways to reduce exposure to the dust. An important component of that program is a guidance document titled, “Controlling Silica Exposures In Construction.”

This guidance, along with the following OSHA recommendations, will assist you in protecting workers from silicosis:

• Be sure to use all available engineering controls such as blasting cabinets, water sprays and local exhaust ventilation. Substitution of less hazardous materials can also be used.
• Be aware of the health effects of crystalline silica and that smoking adds to the damage.
• Know the work operations where exposure to crystalline silica may occur.
• Use type CE positive pressure abrasive blasting respirators for sandblasting.
• For other operations where respirators may be required, workers should wear a respirator approved for protection against crystalline silica containing dust. Do not alter the respirator in any way. Workers who use tight-fitting respirators cannot have beards/mustaches which interfere with the respirator seal to the face.
• If possible, workers should change into disposable or washable work clothes at the work site, then shower and change into clean clothing before leaving the work site.
• Do not eat, drink, use tobacco products, or apply cosmetics in areas where there is dust containing crystalline silica.
• Wash hands and face before eating, drinking, smoking, or applying cosmetics outside of the exposure area.

You can download a PDF of Controlling Silica Exposures In Construction at www.osha.gov/Publications/3362silica-exposures.pdf.

Sources: World Health Organization and Occupational Safety and Health Administration