851 Silica Dust Safety in Construction

Visible and Respirable Dust

Respirable dust particles pose the greatest risk because they are not visible. They are are so small they can get deep into the lungs.

When exposed to silica dust, it's important to remember the following:

• Most dust-generating construction activities produce a mixture of visible and respirable particles.
• You should use visible dust as a general guide for improving dust suppression efforts. If you see visible dust being generated, emissions of respirable silica are probably too high.
• Methods that control tool-generated dust at the source can reduce all types of particle emissions, including respirable particles.
• Do not rely only on visible dust to assess the extent of the silica hazard. There may be more airborne respirable dust present that is not visible to the naked eye.

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