Combustible Dust

Dust is defined as solid particles that are generated by some type of mechanical action on organic or inorganic materials. These mechanical actions include, but are not limited to, handling, crushing and grinding. Dust particles that are too large to remain airborne will settle out, while the smallest ones can remain suspended indefinitely. 

In general terms, a combustible dust is a combustible solid particle having an effective diameter of 420 microns (μm) or smaller and is capable of being suspended in air.

Combustible Dust

Tab/Accordion Items

What are the hazards associated with combustible dust?

Combustible dusts when suspended in air in sufficient concentration can result in a fire or explosion when ignited by an ignition source, such as a flame or electric arc, resulting in extensive property damage and serious human injury and death.

What can I do to protect myself?

Your employer is required to conduct a workplace hazard assessment, a part of which should include the identification of processes and materials that are capable of producing combustible dust. In addition, the employer is also responsible to inform employees about the physical hazards, as well as the health hazards, associated with any materials used in the workplace.

What resources are available to assist employers?

Safety and Health Programs

Several example checklists and programs pertaining to combustible dust can be downloaded and customized to fit the workplace. They include the self-inspection checklisthazard communication programPPE hazard assessmentrespiratory protection program, and confined space entry program

Training and Outreach Services

Presentations on hazard communication, respiratory protectionconfined spaces, and personal protective equipment can be downloaded and customized to fit your training needs.

In addition, the education, training and technical assistance bureau provides free online safety and health training and outreach services (i.e., speaker's bureau requests, safety booths) upon request. 

Lastly, the NCDOL Library offers free safety and health videos (including streaming video services) and related research assistance on consensus standards (i.e., ANSI, NFPA, NEC).

A-Z Safety and Health Topics

Related resources can be found on the A-Z topics pages for respiratory protection, hazard communication, confined spaces, and personal protective equipment

Consultation Services

The consultative services bureau provides free and confidential onsite consultation regarding worksite safety and health hazards.

What regulations apply?

OSH has adopted the following standards that are applicable to combustible dusts. Note: Please also check the standards information and activity webpage to see if there has been any recent or upcoming regulatory activity on this topic. 

General Industry

General Duty Clause

The General Duty Clause located in N.C.G.S. 95-129(1) can be invoked for the protection of employees against recognized serious hazards such as combustible dusts for which no OSH standard exists.

Other Applicable Standards

The Which OSHA Standards Apply webpage can help identify other standards that may be applicable to your worksite.

Where can I learn more?

Industry Guides

Compliance Documents

  • Compliance Directive: CPL 03-00-008 establishes enforcement policy regarding combustible dust and identifies applicable standards and laws and an explanation of the application of these to ensure uniform enforcement.

Hazard Alerts

Technical Assistance

If you would like to receive interpretive guidance on this or any other OSH standard or topic, you can submit your questions using the Ask OSH web form, by e-mail to or by calling 919-707-7876.