Silica Dust: What You Can't See Can Hurt You

What silica dust is

Respirable crystalline silica is a fine dust generated when workers cut, grind, drill, or abrade materials containing silica — concrete, masonry, rock, sand, and quartz. The particles are small enough to reach deep lung tissue and, with repeated exposure, cause irreversible scarring called silicosis. There is no cure.

Where silica exposure occurs

High-risk tasks include: concrete cutting with angle grinders or saws, jackhammering concrete or masonry, tuck-pointing, dry sweeping dusty work areas, drilling rock, and operating equipment that disturbs silica-containing soil. If the task generates visible dust from these materials, assume silica exposure.

OSHA's exposure limit

OSHA's permissible exposure limit (PEL) for respirable crystalline silica is 50 micrograms per cubic meter as an 8-hour TWA — about half the previous limit. The action level is 25 μg/m³. At or above the action level, medical surveillance and enhanced controls are required.

Controls — in order

Wet methods (wetting the material before cutting or grinding) significantly reduce dust generation and should be used whenever feasible. Local exhaust ventilation on tools captures dust at the source. Respiratory protection — a minimum N95 half facepiece, fitted and tested — is required when engineering controls alone can't reduce exposure to the PEL. Never dry sweep or use compressed air to clean silica dust.

Discussion question

What tasks are we doing today that could generate silica dust, and are the appropriate controls — wet methods, vacuum systems, or respiratory protection — in place before work starts?

Documentation

Record this meeting: date, topic ("Silica Dust: What You Can't See Can Hurt You"), attendee names, and facilitator. Documented training records — including toolbox talks — can be relevant in OSHA penalty proceedings, as evidence of an active safety program.