Limits for Coal Dust and Amorphous Silica

Permissible Exposure Limit for Coal Dust (with silica and without)

Under the General Industry Standard, coal dust is regulated as a separate substance, and the

    PEL for coal dust containing greater than 5% silica is a calculated value.
    Refer to the following pages for the specific PELs:

         General Industry – 1910.1000 Table Z-3
         Construction –  1926.55 Appendix A
         Maritime –  1915.1000 Table Z-Shipyard

Permissible Exposure Limit for Amorphous (non-crystalline) Silica

Exposure limits for amorphous silica are listed under the individual standards. Refer to the following pages for the specific PELs:

         General Industry –   1910.1000 Table Z-3
         Construction –  1926.55 Appendix A
         Maritime –  1915.1000 Table Z-Shipyard

The PEL for amorphous silica is expressed by a formula that reduces the amount of dust to which a worker can be exposed  as the percentage of amorphous silica in the dust rises. The term SiO2 refers to the percentage of amorphous silica in the sample. When the amorphous silica content is at or below 5.33% the total dust (Particulates Not Otherwise Regulated) PEL of 15 mg/m3 should be used.  A discussion of this topic is provided in the Interpretation.

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