Is My Dust Combustible? How to Find Out Before Your DHA

By DHA Report Group · Updated October 20, 2026

You have dust in your plant, and someone has asked whether it is combustible. Maybe it was your insurer, a customer, or your own safety team getting ready for a dust hazard analysis (DHA). You can get most of the way to an answer from your desk. Here is how to work through it, and where only a lab test settles the question.

What your Safety Data Sheet does and does not tell you

Start with the Safety Data Sheet (SDS) for each material you handle. Look for wording such as “may form combustible dust concentrations in air,” and check the fire and physical property sections for any dust data.

An SDS has limits, though:

• It describes the product as shipped. Pellets, sheet, bar stock, and whole grain are not dust. Your process may turn them into a fine dust the SDS never describes.
• Silence is not a no. Many Safety Data Sheets say nothing about dust either way. That usually means nobody recorded it, not that the dust was tested and passed.
• Test data is rare. Few list dust test results. When they do, the sample tested may not look like the dust in your plant.

Treat the SDS as a first clue, not a final answer.

Materials that usually are combustible, and ones that are not

Your material family tells you a lot. These are usually combustible as a fine dust:

• Organic materials. Wood, paper, grain, flour, sugar, starch, spices, feed, and textile fibers.
• Many metals. Aluminum, magnesium, titanium, and zirconium, along with fine iron and zinc.
• Plastics and resins. Powders, regrind fines, and powder coatings.
• Some chemicals and carbon materials. Sulfur, many organic chemical powders, coal, and carbon black.

These usually are not combustible: sand, cement, glass, and most minerals such as limestone and gypsum.

Watch for mixtures. A mineral dust blended with an organic binder, or mixed with wood, paper, or plastic dust, can behave differently from the mineral alone.

Why particle size and moisture matter

The same material can give you two different answers depending on its condition.

• Particle size. Finer dust has more surface area and ignites more easily. Coarse chips and pellets behave differently, but cutting, sanding, grinding, and conveying all create fines. The fine fraction is what counts.
• Moisture. Damp dust is harder to ignite. Dust that leaves your process damp can dry out as it sits on warm equipment or high surfaces.

So ask yourself where your finest, driest dust ends up. That is usually your dust collector, the tops of equipment, and overhead surfaces. That dust is what you are trying to characterize.

What a go/no-go screening test tells you

If the SDS and the material family leave you unsure, a go/no-go screening test tells you whether your dust is explosible at all. A lab disperses a sample of your dust in a test chamber with an ignition source and records whether it ignites. You get a yes or a no.

Two things make the result useful:

1. Send a representative sample. Collect the fine dust from where it settles in your plant, not raw material from the bag.
2. Ask how the lab will prepare it. Sample preparation affects the result, so have the lab explain what it tested and why.

A “go” result does not give you design numbers. Those come from further tests for Kst, Pmax, MEC, and MIE. You can read what each one means in our guide to combustible dust testing.

Your DHA can treat the dust as combustible without testing

You do not have to test before you start. A DHA can treat a dust as combustible without testing. For flour, sugar, wood, or aluminum fines, that is often the practical path, because the answer is not in doubt.

Two cautions apply:

• Borderline materials need a test. If you believe your dust is not combustible and the evidence is mixed, only testing settles it. Assuming it is combustible may leave you carrying safeguards you do not need. Assuming it is not, without data, leaves the question open.
• Published tables are for screening only. Protection design needs lab testing of your actual dust, because particle size and moisture shift the numbers.

If you are still working out whether a DHA applies to you, start with does my facility need a dust hazard analysis. For how a study is quoted, see what a DHA costs.

When you do not need us

If all you need is a yes or a no on one material, a dust testing lab answers that. You do not need a DHA to order a screening test.

If everything you handle is plainly mineral, such as sand, cement, or stone, with nothing organic mixed in, you likely do not need a DHA at all.

A DHA makes sense once you know, or are willing to assume, that your dust is combustible and you want to understand where it creates a hazard in your process.

Keep reading

• NFPA 660 Guide: Which Chapter Covers Your Facility
• Dust Hazard Analysis (DHA) for Metal Dust
• Dust Hazard Analysis (DHA) for Plastics, Resins, and Regrind
• Dust Hazard Analysis (DHA) for Woodworking Shops and Mills

Questions about whether your dust is combustible

Does my Safety Data Sheet tell me if my dust is combustible?

Sometimes. An SDS may flag a combustible dust hazard, but many are silent, and most describe the product as shipped instead of the dust your process makes.

Is sand or cement dust combustible?

No. Sand, cement, and most mineral dusts do not burn, though a blend that includes organic material deserves a closer look.

What is a go/no-go test?

It is a lab screening test that shows whether a sample of your dust is explosible at all. The result is a yes or a no, not a set of design numbers.

Do I have to prove my dust is combustible before a DHA?

No. A DHA can treat a dust as combustible without testing. Testing is what settles a borderline material and supports protection design.

Can a published Kst table tell me if my dust is combustible?

Published Kst and Pmax tables are for screening only. Particle size and moisture shift the numbers, so protection design needs lab testing of your actual dust.