What are the Possible Exposure Sources?

Crystalline silica can be found in certain types of natural materials, such as:

  • Sand
  • Soil and rock
  • Gravel
  • Sandstone
  • Slate
  • Granite
  • Clay
  • Ceramic and terracotta tiles
  • Concrete and concrete block
  • Manufactured stone
  • Roof tiles
  • Bricks and blocks
  • Grouts and mortar
  • Some joint compounds
  • Abrasive materials

These become some of the sources of exposure associated with a number of the construction trades.

Exposure Levels

Airborne exposure to crystalline silica dust can depend on a number of things, such as:

1. Types of Activities

Cutting, Drilling and Coring

  • Concrete
  • Roof tile
  • Tile backer board
  • Brick and block
  • Granite

Grinding, Sanding and Sandblasting

  • Sack and patch
  • Tuck point grinding
  • Scabbling/scarifying
  • Drywall mud sanding
  • Hand-held surface grinding

Pulverizing

  • Jack and chipping hammers
  • Cement truck cleaning
  • Concrete recycling
  • Road milling
  • Backhoes, excavators
  • Demolition

Mixing (dry)

  • Cement
  • Plaster and grout

Cleaning Up

  • Dry sweeping (versus wet)
  • Compressed air (versus vacuum)
  • Hauling

2. Location

  • Outside or in a wide open area versus inside or an enclosed area

3. Materials Being Used

  • The percentage of silica present varies a lot. The higher the content, the more likely overexposure will occur

4. Types of Equipment Used

  • Cutting using wet methods versus dry methods
  • Types of blades or abrasives used
  • Use of local ventilation that prevents or reduces the amount of dust you breathe

5. How Long the Dust-Generating Activity Goes on in a Shift

  • The longer the duration of exposure, the greater the chance of overexposure

6. Weather Conditions

  • Presence of moisture
  • The lighter the wind the less likely airborne dust generated will move away from the breathing zone and be quickly diluted. On the flip side, wind currents can move the hazard away from one person to another.

Allowable Exposure Levels

Go to Respirable Crystalline Silica Standards - Important Update for guidance.

Additional Sources of Exposure Information:

June 2019