By DHA Report Group · Updated October 20, 2026
For years, combustible dust requirements were spread across several NFPA standards, and figuring out which ones applied to your facility took real effort. NFPA 660 pulls them into one document. If you have a dust hazard analysis (DHA) on file, or you are about to get one, here is what you need to know.
What NFPA 660 replaced
NFPA 660 consolidates six standards. Each link explains where that standard went and what it means for your DHA:
- NFPA 652: the fundamentals of combustible dust, including the DHA requirement. Now Chapters 1 through 10.
- NFPA 61: agricultural and food processing. Now Chapter 21.
- NFPA 484: combustible metals. Now Chapter 22.
- NFPA 655: sulfur. Now Chapter 23.
- NFPA 664: wood processing and woodworking. Now Chapter 24.
- NFPA 654: combustible particulate solids not covered elsewhere. Now Chapter 25.
NFPA 68 (deflagration venting) and NFPA 69 (explosion prevention systems, including isolation and suppression) were not folded in. They remain separate standards that NFPA 660 references.
How it is organized
NFPA 660 puts the fundamentals that always apply up front, in Chapters 1 through 10, including the DHA requirement (Chapter 7), management systems, hazard management, and emergency planning. Industry-specific requirements for food and agriculture, metals, sulfur, wood, and other materials follow in their own chapters, applied along with the fundamentals. The practical benefit: one document to work from instead of reconciling several. For the full chapter map, see the NFPA 660 guide.
What stayed the same
The core expectations carried over:
- A DHA performed or led by a qualified person
- A DHA review at least every five years and whenever your process changes (see DHA revalidation)
- Housekeeping, ignition source control, and explosion protection based on the hazards you have
- Management of change, training, and documentation
If your facility was already in good shape under NFPA 652 and your industry standard, you are not starting over.
What changed in practice
- References. Section numbers and cross-references are different. A DHA that cites NFPA 652 and 654 sections will not line up with NFPA 660 section numbers.
- One source of truth. Your DHA, your procedures, and your records can all point to one document.
- Clearer path for mixed operations. Facilities that handle more than one material type, like wood and metal, now work from one document.
What it means for your DHA
NFPA 660 ties DHA reviews to two triggers: at least every five years, and whenever your process changes.
- If your DHA was written to the old standards, write your next review to NFPA 660 when either trigger comes due, and update the old section references as part of it.
- If your DHA is five years old or more, or your process has changed, that review is due now.
- If you do not have a DHA, a new one should be written to NFPA 660 from the start.
For what a DHA involves and costs, see what a DHA costs in 2026 and does your facility need a DHA.
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Questions about NFPA 660
What is NFPA 660?
The NFPA Standard for Combustible Dusts and Particulate Solids. It consolidates NFPA 61, 484, 652, 654, 655, and 664.
Did NFPA 660 replace NFPA 68 and 69?
No. NFPA 68 and 69 remain separate standards. NFPA 660 references them.
Do I need a new DHA because the standard changed?
NFPA 660 ties DHA reviews to two triggers: at least every five years, and whenever your process changes. When your next review is due, write it to NFPA 660 and update the old section references.
Did the DHA requirements change under NFPA 660?
The core expectations carried over: a qualified person, a review at least every five years and whenever the process changes, and safeguards based on your hazards. The organization and section numbers changed.