Silica dust
Fine dust generated by cutting, grinding, drilling, or demolishing concrete. The respirable fraction causes silicosis, lung cancer, and kidney disease.
What does silica dust mean?
The hazardous particles are too small to see and remain airborne long after visible dust settles, so a clear-looking work area is not evidence of safety. Federal regulation requires engineering controls such as water delivery or on-tool vacuum extraction, a written exposure control plan, and training. Dry sweeping and compressed-air cleanup are restricted because they re-suspend settled dust.
In practice
A crew dry-cutting a slab with no water and no vacuum is generating exposures many times the legal limit within minutes.