Types of Silica

Crystalline silica may be of several distinct types. Quartz, a form of silica and the most common mineral in the earth’s crust, is associated with many types of rock. Other types of silica include cristobalite and tridymite.

Potential for Exposure During Construction

Concrete and masonry products contain silica sand and rock containing silica. Since these products are primary materials for construction, construction workers may be easily exposed to respirable crystalline silica during activities such as the following:

• Chipping, hammering, and drilling of rock
• Crushing, loading, hauling, and dumping of rock
• Abrasive blasting using silica sand as the abrasive
• Abrasive blasting of concrete (regardless of abrasive used)
• Sawing, hammering, drilling, grinding, and chipping of concrete or masonry
• Demolition of concrete and masonry structures
• Dry sweeping or pressurized air blowing of concrete, rock, or sand dust

Even materials containing small amounts of crystalline silica may be hazardous if they are used in ways that produce high dust concentrations.