Combustible Dust Labeling Requirements

OSHA’s newly published interpretation went back to the Hazard Communication Standard (HCS) to provide even more clarification concerning Combustible Dust.

Most of this discussion is relevant to manufacturers and importers who have to provide the SDS and labels, but the Workplace Labels focuses on the requirements of the user after processing the product and creating a combustible dust hazard.


Combustible Dust became a sticking point in the update to the HCS because it is a recognized hazard where OSHA had already provided guidance in a Combustible Dust National Emphasis Program (NEP) and through voluntary consensus standards like the National Fire Protection Association (NFPA).

But in adjusting with the UN’s Globally Harmonized System (GHS) because it did not have a classification for combustible dust – both the UN and OSHA are in the process of developing a rule for Combustible Dust – OSHA included Combustible Dust into the definition of Hazardous Chemical for the time being.

Combustible Dust Definition

Combustible Dust is a solid combustible material of distinct particles that “presents a fire or deflagration hazard when suspended in air or some other oxidizing medium over a range of concentrations regardless of particle size or shape.”

The NFPA, FM-Global, and ASTM International have various recognized tests, data and criteria to determine Combustible Dust.

Inspectors Guidance

In December, inspectors were given guidance on how to determine if manufacturers and importers were properly classifying their products for combustible dust hazards.

  • Lab tests described in the ASTM E1226, ASTM E1515, and OSHA’s Combustible Dust NEP.
  • Published test results of materials found to be a Combustible Dust such as this OSHA Poster or lists provided by the NFPA.
  • Dust particle size like the NFPA 654 definition used in early OSHA guidance: “finely divided solid material 420 microns or smaller in diameter that presents a fire or explosion hazard when dispersed and ignited in air.”

Clarifications on Reporting Requirements

OSHA provided clarifications on creating a hazard statement, SDS, and labels on shipped containers and in the workplace for Combustible Dusts.

For chemicals that pose a combustible dust hazard when processed but not in the current shipped form the responsible party may include additional language with the hazard statement when it provides further detail and does not contradict or cast doubt on the validity of the standardized hazard information.

The HCS allows for the required label to be only on the first shipment, but OSHA encourages providing product identifier and contact information on each shipped product.

Workplace Labels

  • Grinders (or legally, stationary process containers) that will create a combustible dust hazard while processing the chemical need a workplace label, or employee accessible sign or written material.
  • Non-stationary process containers that will create a combustible dust hazard while processing the chemical, need a label.
  • Boards or pipes that might create a combustible dust hazard when cut do not need to be labeled, but OSHA encourages signs or placards advising workers of the hazards.

New Interpretations

In addition to creating new and updating current regulations, OSHA publishes interpretations and answers to questions about existing rules.

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